Forskolin opposes (ET-1)–induced increase in stress fibers and focal adhesions. Treatment of serum-starved cells with ET-1 (100 nM) increased the staining for stress fibers compared with untreated cells (B vs. A) with a concomitant increase in the staining for MLC phosphorylation (F) and vinculin (J, arrows). Forskolin (10 μM) + rolipram (50 μM) opposed both the basal and the (ET-1)–induced increase in stress fibers (C, D vs. B), ppMLC (G, H vs. F), and focal adhesions (K, L vs. J). The images are representative of three independent experiments.