GTPase activator for the Rho-type GTPases by converting them to an inactive GDP-bound state. Has strong activity toward RHOA, and weaker activity toward RAC1 and CDC42. May act as a specific effector of RAP2A to regulate Rho (By similarity). In concert with RASIP1, suppresses RhoA signaling and dampens ROCK and MYH9 activities in endothelial cells and plays an essential role in blood vessel tubulogenesis (By similarity). Interacts with PTPN13/PTPL1. Interacts with RAP2A via its coiled coil domain (By similarity). Interacts with RASIP1 (By similarity).