Rac GTPase-activating protein 1 (RACGAP1), localized in the mitotic spindle, has guanosine triphosphatase-activating protein (GAP) activity for the Rho family GTPases. This protein binds activated forms of Rho GTPases and stimulates GTP hydrolysis, which results in negative regulation of Rho-mediated signals. This protein plays a regulatory role in cytokinesis, cell growth, and differentiation.
