Unilateral presentation of three muscle variants in the pectoral region

A rare case of three muscle anomalies in the pectoral region was discovered during routine dissection of an 85-year-old female cadaver. The muscle anomalies include the congenital partial absence of the pectoralis major muscle, a sternalis muscle, and a pectoralis quartus muscle. All three variants presented on the right side. The pectoralis major muscle demonstrated a normal clavicular head but lacked an abdominal part and had a sternocostal head that attached only to the manubrium. The sternalis arose from the manubrium and appeared to share a common tendon with the contralateral sternocleidomastoid muscle. The pectoralis quartus arose from the costal cartilages of ribs six and seven and inserted onto the fascia of the coracobrachialis muscle deep to the pectoralis major muscle. The sternalis muscle was innervated by intercostal nerves and the pectoralis quartus was innervated by both the medial pectoral and intercostal nerves. The documentation of pectoral muscle variants is not only important for the anatomical record but has clinical implications for surgical procedures in the axillary region and the interpretation of CT and MRI scans

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Epidermal growth factor stimulates serine/threonine phosphorylation of the focal adhesion protein paxillin in a MEK-dependent manner in normal rat kidney cells.

Epidermal growth factor (EGF)-stimulated proliferation of renal epithelial cells plays an important role in the recovery of kidney tubule epithelia following exposure to insult. Numerous studies have demonstrated that tyrosine phosphorylation of the focal adhesion protein paxillin mediates in part the effects of growth factors on cell growth, migration, and organization of the actin-based cytoskeleton. The experiments in this report were designed to determine the effect of EGF on paxillin phosphorylation in normal rat kidney (NRK) epithelial cells. Interestingly, treatment of NRK cells with EGF stimulated paxillin serine/threonine phosphorylation, which caused a reduction in the mobility of paxillin on sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE). The EGF-stimulated mobility shift of paxillin was independent of an intact cytoskeleton, phosphatidylinositol 3-kinase (PI 3-kinase) activation, protein kinase C (PKC) activation, and cellular adhesion. However, inhibitors of the mitogen-activated protein kinase/extracellular signal-regulated kinase kinase abrogated the EGF-stimulated change in paxillin mobility. In addition, the EGF-stimulated change in paxillin serine/threonine phosphorylation was not accompanied by a profound reorganization of the actin cytoskeleton. These results identify paxillin as a component EGF signaling in renal epithelial cells and implicate members of the MAP kinase pathway as critical regulators of paxillin serine/threonine phosphorylation.