Targets myosin phosphatase to the actin cytoskeleton. Required for the regulation of the actin cytoskeleton by RhoA and ROCK1. Depletion leads to an increased number of stress fibers in smooth muscle cells through stabilization of actin fibers by phosphorylated myosin. Overexpression of MRIP as well as its F-actin-binding region leads to disassembly of stress fibers in neuronal cells. UniProtKB P97434Surks H.K., J. Biol. Chem. 278:51484-51493(2003).Koga Y., J. Biol. Chem. 280:4983-4991(2005).Inazawa J., Submitted (DEC-2002) to the EMBL/GenBank/DDBJ databases.