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. It phosphorylates and activates LIM kinase which in turn phosphorylates cofilin, inhibiting its actin-depolymerizing activity. It is also essential in cytokinesis and plays a role in transcriptional activation by serum response factor. 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.
