The RHO (see ARHA; MIM 165390) family of small GTPases are involved in signal transduction through transmembrane receptors, and they are inactive in the GDP-bound form and active in the GTP-bound form. GTPase-activating proteins, such as ARHGAP23, inactivate RHO family proteins by stimulating their hydrolysis of GTP (Katoh and Katoh, 2004 [PubMed 15254754]).[supplied by OMIM, Mar 2008].