ABSTRACT
<p><b>OBJECTIVE</b>To analyze the upstream region of radiation-induced junB gene.</p><p><b>METHODS</b>Four plasmids containing 250 bp, 590 bp, 900 bp and 1650 bp, and CAT reporter gene were constructed separately and introduced to L8704 cells. The cells were irradiated with 2 Gy X-rays and incubated at different intervals. Total RNA was extracted from the cells and fluctuation of the CAT mRNA level was assessed by the RNA ratio of CAT/beta-actin measured by quantitative Northern blot hybridization.</p><p><b>RESULTS</b>CAT mRNA expression containing 900 bp and 1560 bp junB promoter remarkably and rapidly increased, and reached its peak 30 min after 2 Gy X-ray irradiation.</p><p><b>CONCLUSIONS</b>590-900 bp fragments located in the upstream region of junB gene play an important role in the early process of cells against radiation.</p>