Gel shift of electrophoresis and Northern and Western blotting analysis were used to detect the effect of c-iun antibody on the interact between AP-1 site of ET-1 gene and nuclear proteins as well as the effect of TPA on c-fos/c-jun gene expression. The results showed that AP-1 binding activity in vascular endothelial cells was stimulated by c-fos/c-jun, whose expression was induced by TPA, and that the electrophoretic mobility of band of DNA-protein complexes was altered by the antibody against c-jun. These results suggest that ET-1 gene expression induced by TPA is mediated by c-fos/c-jun.