Cultured astrocytes were serum deprived for 18 h and incubated with 100 nm ET-1 for different times (1–30 min). Cells were then harvested and processed for P-c-jun Western blot. Data were obtained from x-ray P-c-jun densitometry and are expressed as fold increase in ET-1-induced c-Jun phosphorylation over unstimulated cells (time 0). Data are averages ± SEM of three independent experiments performed on separate astrocyte cultures. *p < 0.05; **p < 0.001 (Student's t test).