expression of protooncogene cjun p38 and proliferating cell nuclear antigen in intestinal epithelial cells in rats different development stages objective to investigate the expression characteristics of protooncogene cjun and its related gene p38 in different developmental intestinal epithelial cells in rats and to explore their biological roles in the intestinal wound healing after injurymethods immunohistochemical techniques were used to detect the expressions of cjun p38 and proliferating cell nuclear antigen pcnaresults the positive expression of cjun in intestinal epithelial cells at the early development stage from e14 d to p28 d was much stronger and more extensive than that in mature rats and migrated from bottom to top of villus with epithelial cellular development the positive expression of pcna was similar with cjun during the same time but the distinction between them was location of their expression the expression of cjun in mature rat only lay in the top of villus while the expression of pcna was limited to intestinal crypts the expression of p38 during stages of development and mature mainly was in mitogenic cellsconclusion the results indicate that the strong expression of tumor gene cjun at the early development and mature stages of intestinal epithelial cells at the special region is related to cellular differentiation and p38 is probable correlate with cellular mitogenesis