The Rho family of GTP-binding proteins plays a role in the development of neuronal structure. The activation of the GTP-bound form is regulated by GTPase-activating proteins, which stimulate GTP hydrolysis, leading to inactivation. GMIP (Gem-interacting protein) is a 970 amino acid protein that stimulates the GTPase activity of RhoA in vitro and in vivo. GMIP interacts with Gem through its N-terminus and has a Rho GTPase-activating protein domain at its C-terminus. GMIP is able to inhibit RhoA function, leading to Actin cytoskeletal reorganization in vivo. Encoded by a gene that maps to human chromosome 19p13.11, GMIP contains one phorbol-ester/DAG-type zinc finger and one Rho-GAP domain.