Two Rho-associated kinases (ROCK), ROCK-I and ROCK-II, act downstream of the G protein Rho to regulate cytoskeletal stability. The ROCKs play important roles in diverse cellular functions including cell adhesion and proliferation, smooth muscle contraction, and stem cell renewal. 3-(4-Pyridyl)indole is a ROCK-I inhibitor (IC50 = 25 μM) that promotes cell spreading, inhibits membrane blebbing, and induces dissolution of actin stress fibers in a wound healing assay. It also inhibits ROCK-II and PRK2, another Rho-dependent kinase, with similar potency, while inhibiting MSK-1 and PKA with relatively weaker potency.
