Rho, the Ras-related small GTPase, is responsible for the regulation of Actinbased
cytoskeletal structures including stress fibers, focal adhesions and
the contractile RING apparatus. Rho proteins function as molecular switches
that are able to turn cytokinesis on and off. Although little is known about
signaling downstream of Rho, a host of putative Rho effector proteins have
been described, including rhophilin, Rhotekin, citron and the serine/threonine
kinase, protein kinase N. Two additional Rho-activated serine/threonine
kinases have been described, designated Rock-1 and Rock-2 (also referred
to as Roka) for Rho-associated coil-containing protein kinase. Rock-1 and
Rock-2 share a structural similarity with myotonic dystrophy kinase.