Brain network analysis of interictal epileptiform discharges from ECoG to identify epileptogenic zone in pediatric patients with epilepsy and focal cortical dysplasia type II: A retrospective study.

Objective: For patients with drug-resistant focal epilepsy, intracranial monitoring remains the gold standard for surgical intervention. Focal cortical dysplasia (FCD) is the most common cause of pharmacoresistant focal epilepsy in pediatric patients who usually develop seizures in early childhood. Timely removal of the epileptogenic zone (EZ) is necessary to achieve lasting seizure freedom and favorable developmental and cognitive outcomes to improve the quality of life. We applied brain network analysis to investigate potential biomarkers for the diagnosis of EZ that will aid in the resection for pediatric focal epilepsy patients with FCD type II. Methods: Ten pediatric patients with focal epilepsy diagnosed as FCD type II and that had a follow-up after resection surgery (Engel class I [n = 9] and Engel class II [n = 1]) were retrospectively included. Time-frequency analysis of phase transfer entropy, graph theory analysis, and power spectrum compensation were combined to calculate brain network parameters based on interictal epileptiform discharges from ECoG. Results: Clustering coefficient, local efficiency, node out-degree, and node out-strength with higher values are the most reliable biomarkers for the delineation of EZ, and the differences between EZ and margin zone (MZ), and EZ and normal zone (NZ) were significant (p < 0.05; Mann-Whitney U-test, two-tailed). In particular, the difference between MZ and NZ was significant for patients with frontal FCD (MZ > NZ; p < 0.05) but was not significant for patients with extra-frontal FCD. Conclusions: Brain network analysis, based on the combination of time-frequency analysis of phase transfer entropy, graph theory analysis, and power spectrum compensation, can aid in the diagnosis of EZ for pediatric focal epilepsy patients with FCD type II.

Wasting condition as a marker for severe disease in pediatric Crohn's disease.

ABSTRACT: Several studies have shown an association between sarcopenia and clinical outcomes in patients with Crohn's disease (CD). However, studies have shown different results, and the association between prognosis and wasting conditions in pediatric patients with CD is uncertain. In this study, we evaluated the clinical significance of wasting in pediatric CD patients.We retrospectively analyzed data on wasting syndrome in patients diagnosed with CD at the Pediatric Department of Gachon University Gil Medical Center between January 1995 and January 2018.Of 105 patients diagnosed with CD, 39.0% were classified into the wasting group (weight-for-age z-score ≤-1) and 61.0% into the nonwasting group (weight-for-age z-score >-1). Height-for-age and body mass index-for-age z-scores at the time of diagnosis were significantly associated with wasting (P < .001 and P < .001, respectively). Additionally, wasting was significantly associated with low levels of hemoglobin (P < .001), high levels of inflammatory markers, including C-reactive protein (P = .005) and erythrocyte sedimentation rate (P = .04), and a smaller surface area of the gluteus maximus muscle (P < .001). Interestingly, since the site of CD involvement and other markers for nutrition did not correlate with wasting syndrome, wasting appears to be a marker for the severity of pediatric CD. Lastly, the wasting group tended to have a greater use of biologic therapy after first-line therapy failed to improve wasting syndrome.Wasting syndrome, including sarcopenia, can serve as a marker for the severity of pediatric CD.

Efficacy of the Ketogenic Diet for Pediatric Epilepsy According to the Presence of Detectable Somatic mTOR Pathway Mutations in the Brain.

BACKGROUND AND PURPOSE: A multifactorial antiepileptic mechanism underlies the ketogenic diet (KD), and one of the proposed mechanisms of action is that the KD inhibits the mammalian target of rapamycin (mTOR) pathway. To test this clinically, this study aimed to determine the efficacy of the KD in patients with pathologically confirmed focal cortical dysplasia (FCD) due to genetically identifiable mTOR pathway dysregulation. METHODS: A cohort of patients with pathologically confirmed FCD after epilepsy surgery and who were screened for the presence of germline and somatic mutations related to the mTOR pathway in peripheral blood and resected brain tissue was constructed prospectively. A retrospective review of the efficacy of the prior KD in these patients was performed. RESULTS: Twenty-five patients with pathologically confirmed FCD and who were screened for the presence of detectable somatic mTOR pathway mutations had received a sufficient KD. Twelve of these patients (48.0%) had germline or somatic detectable mTOR pathway mutations. A response was defined as a ≥50% reduction in seizure frequency. The efficacy of the KD after 3 months of dietary therapy was superior in patients with detectable mTOR pathway mutations than in patients without detectable mTOR pathway mutations, although the difference was not statistically significant (responder rates of 58.3% vs. 38.5%, p=0.434). CONCLUSIONS: A greater proportion of patients with mTOR pathway responded to the KD, but there was no statistically significant difference in efficacy of the KD between patients with and without detectable mTOR pathway mutations. Further study is warranted due to the smallness of the sample and the limited number of mTOR pathway genes tested in this study.

Clinical characteristics of KCNQ2 encephalopathy.

PURPOSE: KCNQ2 mutations are associated with benign familial neonatal epilepsy (BFNE) or developmental and epileptic encephalopathy (DEE). In this study, we aimed to delineate the phenotype of KCNQ2 encephalopathy and evaluate the treatment response. METHODS: Thirteen patients of KCNQ2 encephalopathy were included in the study. Characteristics of KCNQ2 mutations, electroclinical features, clinical course, and response to the treatment were analyzed. RESULTS: Age range of the thirteen patients was between 3 months and 20.9 years. The onset of seizures in 11 patients ranged from 1 to 3 days of age, while in the other two patients it was 7 and 40 days, respectively. Most common initial seizure types were tonic seizures. Initial EEGs were suppression burst pattern in seven patients and slow and disorganized background with multifocal epileptiform discharges in six patients. Initial epilepsy syndrome was Ohtahara syndrome in seven patients, neonatal focal seizure in five patients, and focal epilepsy beyond neonatal period in one patient. Sodium channel blockers including oxcarbazepine (OXC) (n = 3), lamotrigine (LTG) (n = 3), phenytoin (PHT) (n = 2), topiramate (TPM) (n = 2), and zonisamide (ZNS) (n = 1) were tried and found effective in eleven patients. Ultimately, 12 of 13 patients became seizure-free. However, developmental outcomes were poor. CONCLUSIONS: Sodium channel blockers are effective in seizure control in these patients with KCNQ2 encephalopathy. Early recognition of KCNQ2 encephalopathy and early use of sodium channel blockers might be helpful in seizure control.

Efficacy and prognosis of long-term, high-dose steroid therapy for Lennox-Gastaut syndrome.

OBJECTIVE: Lennox-Gastaut syndrome (LGS) is a severe form of developmental and epileptic encephalopathy that is highly resistant to treatment with conventional anti-epileptic drugs and non-pharmacological therapies. In the present study, we aimed to investigate the efficacy of long-term, high-dose steroid therapy and its effect on prognosis in children with LGS. METHODS: This prospective study included patients with LGS who received long-term, high-dose steroid therapy beginning in November 2016. Prednisolone (60 mg per day) was administered for 2 weeks, following which the dosage was reduced to 60 mg on alternate days for 12 weeks. The drug was then slowly tapered over the next 3 months. The primary outcome was a reduction in seizure frequency relative to baseline at 14 weeks. The secondary outcome was whether patients had become seizure-free at 1 year. RESULTS: Among 44 patients, 30 (68.2%) experienced a reduction in seizure frequency of more than 50%, including 26 (59.1%) with complete seizure control who were classified as the responder group. The remaining 14 (31.8%) were classified as the non-responder group after 14 weeks of treatment. Twenty patients (45.5%, 20/44) remained seizure-free after 1 year of treatment. However, 10 patients (33.3%, 10/30) in the responder group relapsed within a year. Improvements in electroencephalography (EEG) findings tended to be consistent with seizure outcomes. All patients had side effects of weight gain and Cushing's face, but most adverse effects were mild and transient. CONCLUSION: Long-term, high-dose steroid therapy can be considered an effective treatment option for children with intractable LGS.

The phenotype and treatment of SCN2A-related developmental and epileptic encephalopathy.

AIMS: We aimed to delineate the phenotypic spectrum of SCN2A-related developmental and epileptic encephalopathy (DEE) and determine the effectiveness of various treatment modalities, including sodium channel blockers and the ketogenic diet. METHODS: Eleven patients with SCN2A-related DEE were included in the study. The characteristics of SCN2A mutations, electroclinical features, clinical course, and response to treatment modalities were analysed. RESULTS: The 11 patients were aged between 0.4 and 9.7 years. The onset of seizures ranged from neonate (six patients) to infant (four patients), to childhood (one patient). Epilepsy presented as Ohtahara syndrome, West syndrome, epilepsy of infancy with migrating focal seizures (EIMFS), and focal epilepsy in neonatal- to infantile-onset patients. The only childhood-onset patient in our study presented with focal epilepsy with autism. Neonatal-to infantile-onset patients had drug-resistant epilepsy (9/10), however, sodium channel blockers were effective in all treated patients (9/9). The ketogenic diet (6/8) and high-dose steroid treatment (4/5) were also effective. The seizures in the childhood-onset patient worsened during treatment with sodium channel blockers. All mutations in neonatal- to infantile-onset patients were missense mutations, whereas the mutation in the childhood-onset patient was a truncation mutation. CONCLUSIONS: These results support earlier observations regarding the epilepsy syndromes and response to antiepileptic drugs in patients with SCN2A-related DEE.

Development of the Korean Developmental Screening Test for Infants and Children (K-DST).

BACKGROUND: Most developmental screening tools in Korea are adopted from foreign tests. To ensure efficient screening of infants and children in Korea, a nationwide screening tool with high reliability and validity is needed. PURPOSE: This study aimed to independently develop, standardize, and validate the Korean Developmental Screening Test for Infants and Children (K-DST) for screening infants and children for neurodevelopmental disorders in Korea. METHODS: The standardization and validation conducted in 2012-2014 of 3,284 subjects (4-71 months of age) resulted in the first edition of the K-DST. The restandardization and revalidation performed in 2015-2016 of 3.06 million attendees of the National Health Screening Program for Infants and Children resulted in the revised K-DST. We analyzed inter-item consistency and test-retest reliability for the reliability analysis. Regarding the validation of K-DST, we examined the construct validity, sensitivity and specificity, receiver operating characteristic curve analysis, and a criterion-related validity analysis. RESULTS: We ultimately selected 8 questions in 6 developmental domains. For most age groups and each domain, internal consistency was 0.73-0.93 and test-retest reliability was 0.77-0.88. The revised K-DST had high discriminatory ability with a sensitivity of 0.833 and specificity of 0.979. The test supported construct validity by distinguishing between normal and neurodevelopmentally delayed groups. The language and cognition domain of the revised K-DST was highly correlated with the K-Bayley Scales of Infant Development-II's Mental Age Quotient (r=0.766, 0.739), while the gross and fine motor domains were highly correlated with Motor Age Quotient (r=0.695, 0.668), respectively. The Verbal Intelligence Quotient of Korean Wechsler Preschool and Primary Scales of Intelligence was highly correlated with the K-DST cognition and language domains (r=0.701, 0.770), as was the performance intelligence quotient with the fine motor domain (r=0.700). CONCLUSION: The K-DST is reliable and valid, suggesting its good potential as an effective screening tool for infants and children with neurodevelopmental disorders in Korea.

Targeted gene panel sequencing in early infantile onset developmental and epileptic encephalopathy.

BACKGROUND: Early-onset developmental and epileptic encephalopathy (DEE) is characterized by repeated seizures beginning within 3 months of birth and severe interictal epileptiform discharge, including burst suppression. This study assessed the utility of targeted gene panel sequencing in the genetic diagnosis of this disease. MATERIALS AND METHODS: Targeted gene panel sequencing was performed in 150 early infantile-onset DEE patients (≤3 months of age), and we extensively reviewed their clinical characteristics, including therapeutic efficacy, according to genotype. RESULTS: Of the early infantile-onset DEE patients, 70 were neonatal-onset DEE and the other 80 patients began experiencing seizures from 1 to 3 months after birth. There were 11 different pathogenic or likely pathogenic variants among 34.7% (52/150) of patients with early infantile-onset DEE, in whom KCNQ2, STXBP1, CDKL5, and SCN1A were the major pathogenic variants. Among the neonatal-onset DEE patients, pathological genes were identified in 42.9% (30/70), indicating a significantly higher diagnostic yield than in 27.5% (22/80) of patients who experienced seizure onset 1 to 3 months after birth (p = 0.048). Among the neonatal-onset DEE group, variants in KCNQ2, STXBP1, and CDKL5 were detected at high frequencies, accounting for 66.7% (20/30) of the pathogenic or likely pathogenic variants found in this study. CONCLUSION: Targeted gene panel sequencing demonstrated a high yield of pathogenic variants in the diagnosis of early-onset epileptic encephalopathy, especially in those with neonatal-onset DEE. Early diagnosis of early-onset epileptic encephalopathy may improve the prognosis of patients by earlier selection of appropriate treatment based on pathogenic variant.

Genetic and clinical features of SCN8A developmental and epileptic encephalopathy.

OBJECTIVE: We aim to delineate the genetic and clinical features of SCN8A developmental and epileptic encephalopathy. METHODS: Nine patients with SCN8A developmental and epileptic encephalopathy were included in this study. Genetic and clinical features and effectiveness of sodium channel blockers were assessed in patients who were confirmed with SCN8A mutations. RESULTS: The onset of seizures ranged from the neonatal period to 18 months of age. Seizure types were diverse and predominantly involved focal seizures or spasms. The most common initial epilepsy syndrome was West syndrome in four patients, followed by neonatal-onset focal seizures in three patients and unclassified focal epilepsy in two patients. Electroencephalograms (EEGs) showed slow and disorganized background and epileptiform abnormalities with occipital predominance. Six patients presented intractable seizures including one patient with recurrent nonconvulsive status epilepticus. Sodium channel blockers were effective in seven patients among eight patients given them. All patients showed developmental delay or regression. Severe hypotonia or ataxia was also presented in some patients. Microcephaly was also characteristic. De novo missense mutations in SCN8A were found in the inactivation gate, C-terminal, loop 2, and transmembrane segments (S1, 4, 5, and 6). There was no correlation between the location of the mutation in the protein and phenotype or response to sodium channel blockers. CONCLUSION: SCN8A developmental and epileptic encephalopathy presents intractable seizures including spasms, focal seizures, neonatal status epilepticus, and nonconvulsive status epilepticus. Sodium channel blockers were effective irrelevant to the location of the mutation in the protein.

Combination of Early EEG, Brain CT, and Ammonia Level Is Useful to Predict Neurologic Outcome in Children Resuscitated From Cardiac Arrest.

Purpose: Predicting neurologic prognosis in pediatric patients recovered after cardiac arrest is more difficult than in adults. This study hypothesized that a combination model of early electroencephalography, brain computed tomography (CT), and laboratory findings improve prediction performance of neurologic outcome in pediatric patients after cardiac arrest. Methods: We retrospectively analyzed the medical records of pediatric patients resuscitated after non-traumatic cardiac arrest. Clinical features, electroencephalography, gray matter to white matter attenuation ratio on brain CT, and laboratory findings were analyzed. The primary outcome was neurologic prognosis based on the Pediatric Cerebral Performance Category score. Results: Of 21 patients, seven (33.3%) were classified as a good neurologic outcome group and 14 (66.7%) were classified as a poor neurologic outcome group. The good outcome group was associated with a slow and disorganized electroencephalographic background pattern (P = 0.006), reactivity (P = 0.006), and electrographic seizures (P = 0.03). The frequency of a suppressed electroencephalographic background pattern was significantly higher in the poor outcome group (P = 0.006). The poor outcome group was also associated with a low level of gray matter to white matter attenuation ratio (P = 0.03) and hyperammonemia (P = 0.003). The area under curve of the combined model, consisting of electroencephalographic background, gray matter to white matter attenuation ratio, and ammonia was the highest at 0.959 (0.772-0.999) with a specificity of 100%. Conclusion: Unfavorable electroencephalographic background, low gray matter to white matter attenuation ratio on brain CT, and hyperammonemia are associated with poor neurologic outcome in children after cardiac arrest.

Multimodal assessment using early brain CT and blood pH improve prediction of neurologic outcomes after pediatric cardiac arrest.

BACKGROUND: Early prediction of neurologic prognosis in children resuscitated from cardiac arrest is a major challenge. This study aimed to investigate the usefulness of a combined model based on brain computed tomography (CT) and initial blood gas analysis to predict neurologic prognoses in pediatric patients after cardiac arrest. METHODS: We retrospectively analyzed the medical records of patients resuscitated after cardiac arrest from 2000 to 2018. Patients aged one month to 18 years were included. Gray to white matter ratio (GWR), ambient cistern effacement (ACE), and blood gas analysis were studied. The primary outcome was neurological prognosis, which was evaluated using the Pediatric Cerebral Performance Category (PCPC) scale at discharge. RESULTS: Of 97 resuscitated patients, 64 brain CT images were available. Fourteen patients had a good neurologic outcome (PCPC 1-3) and 50 patients a poor neurologic outcome (PCPC 4-6). The multimodal model (AUC 0.897) containing GWR of basal ganglia (BG), ACE, and blood pH was found to be superior for predicting poor neurologic prognosis than single variable models (AUC of GWR-BG: 0.744, ACE: 0.804, pH: 0.747). Interestingly, we found the GWR-BG cutoff value for specificity 100% differed significantly between patients <4 years (cutoff value: 1.08, p = 0.04) and ≥4 years (cutoff value: 1.18, p = 0.004). CONCLUSIONS: The combination of GWR-BG, ambient cistern effacement, and blood pH was found to usefully predict neurological outcome in children resuscitated from cardiac arrest. In addition, the cutoff value of GWR-BG for the prediction of neurologic outcome was found to increase with age.

BPC157 as Potential Agent Rescuing from Cancer Cachexia.

Cancer cachexia, one of the metabolic syndromes caused by cancer, is a devastating and miserable condition encountered in more than 50% of terminal cancer patients presenting with significant weight loss associated with skeletal muscle atrophy and fat loss. Though cachexia may account for up to 20% of cancer deaths, no significant treatment is still lacking and is of urgent unmet medical need in cancer treatment. Therefore, understanding the underlying molecular mechanisms is essential for anticipating therapeutic approaches. Since the primary events driving cachexia are mediated via either the central nervous system relatedor inflammation related-anorexia, hypoanabolism, and hypercatabolism, therapy usually targets nutritional support to compensate reduced food intake along with some anti-inflammatory agents to cover specific inflammation-related metabolic derangement, and encourages exercise to supplement reduced physical activity, but all proven to be not so effective so far. Therefore, combination therapies such as a standard multi-modal package including an anorexic agent, megestrol acetate, and anti-inflammatory agent coupled with the development of potential novel therapeutics promise a new era in rescuing patients from cancer cachexia. In this review, we propose the potential application of BPC157, one of the active cytoprotective agents isolated from gastric juices for cancer cachexia. Before clinical trial, we introduced the evidence showing BPC157 rescued from cancer cachexia supported with explored mode of actions.

CXXC5 is a transcriptional activator of Flk-1 and mediates bone morphogenic protein-induced endothelial cell differentiation and vessel formation.

CXXC5 is a member of a small subset of proteins containing CXXC-type zinc-finger domain. Here, we show that CXXC5 is a transcription factor activating Flk-1, a receptor for vascular endothelial growth factor. CXXC5 and Flk-1 were accumulated in nucli and membrane of mouse embryonic stem cells (mESCs), respectively, during their endothelial differentiation. CXXC5 overexpression induced Flk-1 transcription in both endothelium-differentiated mESCs and human umbilical vein endothelial cells (HUVECs). In vitro DNA binding assay showed direct interaction of CXXC5 on the Flk-1 promoter region, and mutation on its DNA-binding motif abolished transcriptional activity. We showed that bone morphorgenetic protein 4 (BMP4) induced CXXC5 transcription in the cells, and inhibitors of BMP signaling suppressed the CXXC5 induction and the consequent Flk-1 induction by BMP4 treatment. CXXC5 knockdown resulted in suppression of BMP4-induced stress fiber formation (56.8 ± 1.3% decrease, P<0.05) and migration (54.6 ± 1.9% decrease, P<0.05) in HUVECs. The in vivo roles of CXXC5 in BMP-signaling-specific vascular development and angiogenesis were shown by specific defect of caudal vein plex vessel formation (57.9 ± 11.8% decrease, P<0.05) in cxxc5 morpholino-injected zebrafish embryos and by suppression of BMP4-induced angiogenesis in subcutaneously injected Matrigel plugs in CXXC5(-/-) mice. Overall, CXXC5 is a transcriptional activator for Flk-1, mediating BMP signaling for differentiation and migration of endothelial cell and vessel formation.

Sur8/Shoc2 involves both inhibition of differentiation and maintenance of self-renewal of neural progenitor cells via modulation of extracellular signal-regulated kinase signaling.

Sur8/Shoc2 is a scaffold protein that regulates the Ras-extracellular signal-regulated kinase (ERK) pathway. However, the roles of Sur8 in cellular physiologies are poorly understood. In this study, Sur8 was severely repressed in the course of neural progenitor cell (NPC) differentiation in the cerebral cortex of developing rat embryos. Similarly, Sur8 was also critically reduced in cultured NPCs, which were induced differentiation by removal of basic fibroblast growth factor (bFGF). Sur8 regulation occurs at the protein level rather than at the mRNA level as revealed by both in situ hybridization and reverse transcriptase polymerase chain reaction analyses. The role of Sur8 in NPC differentiation was confirmed by lentivirus-mediated Sur8 knockdown, which resulted in increased differentiation, whereas exogenous expression of Sur8 inhibited differentiation. Contrastingly, NPC proliferation was promoted by overexpression, but was suppressed by Sur8 knockdown. The role of Sur8 as an antidifferentiation factor in the developing rat brain was confirmed by an ex vivo embryo culture system combined with the lentivirus-mediated Sur8 knockdown. The numbers and sizes of neurospheres were reduced, but neuronal outgrowth was enhanced by the Sur8 knockdown. The Ras-ERK pathway is involved in Sur8-mediated regulations of differentiation, as the treatment of ERK kinase (MEK) inhibitors blocks the effects of Sur8. The regulations of NPCs' differentiation and proliferation by the Ras-ERK pathway were also shown by the rescues of the effects of bFGF depletion, neuronal differentiation, and antiproliferation by epidermal growth factor. In summary, Sur8 is an antidifferentiation factor that stimulates proliferation for maintenance of self-renewal in NPCs via modulation of the Ras-ERK pathway.

Wnt5a is required for endothelial differentiation of embryonic stem cells and vascularization via pathways involving both Wnt/beta-catenin and protein kinase Calpha.

In this study, we examined the signaling pathways activated by Wnt5a in endothelial differentiation of embryonic stem (ES) cells and the function of Wnt5a during vascular development. We first found that Wnt5a(-/-) mouse embryonic stem (mES) cells exhibited a defect in endothelial differentiation, which was rescued by addition of Wnt5a, suggesting that Wnt5a is required for endothelial differentiation of ES cells. Involvement of both beta-catenin and protein kinase (PK)Calpha pathways in endothelial differentiation of mES cells requiring Wnt5a was indicated by activation of both beta-catenin and PKCalpha in Wnt5a(+/-) but not in Wnt5a(-/-) mES cells. We also found that beta-catenin or PKCalpha knockdowns inhibited the Wnt5a-induced endothelial differentiation of ES cells. Moreover, the lack of endothelial differentiation of Wnt5a(-/-) mES cells was rescued only by transfection of both beta-catenin and PKCalpha, indicating that both genes are required for Wnt5a-mediated endothelial differentiation. Wnt5a was also found to be essential for the differentiation of mES cells into immature endothelial progenitor cells, which are known to play a role in repair of damaged endothelium. Furthermore, a defect in the vascularization of the neural tissue was detected at embryonic day 14.5 in Wnt5a(-/-) mice, implicating Wnt5a in vascular development in vivo. Thus, we conclude that Wnt5a is involved in the endothelial differentiation of ES cells via both Wnt/beta-catenin and PKC signaling pathways and regulates embryonic vascular development.

Valproic acid induces differentiation and inhibition of proliferation in neural progenitor cells via the beta-catenin-Ras-ERK-p21Cip/WAF1 pathway.

BACKGROUND: Valproic acid (VPA), a commonly used mood stabilizer that promotes neuronal differentiation, regulates multiple signaling pathways involving extracellular signal-regulated kinase (ERK) and glycogen synthase kinase3beta (GSK3beta). However, the mechanism by which VPA promotes differentiation is not understood. RESULTS: We report here that 1 mM VPA simultaneously induces differentiation and reduces proliferation of basic fibroblast growth factor (bFGF)-treated embryonic day 14 (E14) rat cerebral cortex neural progenitor cells (NPCs). The effects of VPA on the regulation of differentiation and inhibition of proliferation occur via the ERK-p21Cip/WAF1 pathway. These effects, however, are not mediated by the pathway involving the epidermal growth factor receptor (EGFR) but via the pathway which stabilizes Ras through beta-catenin signaling. Stimulation of differentiation and inhibition of proliferation in NPCs by VPA occur independently and the beta-catenin-Ras-ERK-p21Cip/WAF1 pathway is involved in both processes. The independent regulation of differentiation and proliferation in NPCs by VPA was also demonstrated in vivo in the cerebral cortex of developing rat embryos. CONCLUSION: We propose that this mechanism of VPA action may contribute to an explanation of its anti-tumor and neuroprotective effects, as well as elucidate its role in the independent regulation of differentiation and inhibition of proliferation in the cerebral cortex of developing rat embryos.