ROCK (Rho-associated kinase), a family of serine/threonine kinases, is an important downstream target of Rho-GTPase and plays an important role in Rho-mediated signaling. Two isoforms of ROCK have been identified: ROCK1 and ROCK2. Caspase-3-induced cleavage of ROCK1 and direct cleavage of ROCK2 by granzyme B (grB) activate ROCK and lead to phosphorylation of myosin light chain and inhibition of myosin phosphatase. ROCK2 is a serine/threonine kinase that regulates cytokinesis, smooth muscle contraction, the formation of actin stress fibers, focal adhesions and the activation of the c-fos serum response element. It is a target for the small GTPase Rho.
