Rho effectors and reorganization of actin cytoskeleton

The small GTPase Rho regulates several actomyosin-based cellular processes such as cell adhesion, cytokinesis and contraction. The biochemical mechanisms of these actions remain unknown. Recently, several GTP-Rho binding proteins were isolated. Among them, p140mDia and p160ROCK appear to work as Rho effectors mediating its action on the cytoskeleton. p140mDia induces actin polymerization by recruiting an actin binding protein, profilin, to the site of Rho action. p160ROCK induces focal adhesions and stress fibers by activating integrin and clustering them by the use of myosin-based contractility.