Formation of apoptotic bodies is a typical character of apoptotic cell death, but how the processes are controlled is not known. In this study, we compared two apoptosis inducing systems in vascular endothelial cells (VEC). We found that the formation of apoptotic bodies during apoptosis induced by rattlesnake venom, which is an unique and specific apoptosis inducer to vascular endothelial cells, was much faster than that induced by deprivation of survival factors (aFGF and serum). When we blocked the synthesis of mRNAs in cells treated with rattlesnake venom by DRB (5, 6-dichloro-1-beta-D-ribofuranosylbenzimidazole), an inhibitor of transcription, the formation of apoptotic bodies was dramatically inhibited. We examined the expression of p53 gene and found that its expression was much higher in apoptosis induced by rattlesnake venom than that in apoptosis induced by deprivation of aFGF and serum. Our results suggest that gene expression is important and p53 gene may play a major role in inducing the formation of apoptotic bodies in VEC.