GTPase activator for the Rho-type GTPases by converting them to an inactive GDP-bound state. Has a substantial GAP activity toward CDC42 and RAC1 and less toward RHOA. Has a role in regulating adhesion of hematopoietic cells to the extracellular matrix. Binds phosphoinositides, and has the highest affinity for phosphatidylinositol 3,4,5-trisphosphate, followed by phosphatidylinositol 3,4-bisphosphate and phosphatidylinositol 4,5-bisphosphate. Interacts with FASLG. Predominantly expressed in peripheral blood leukocytes, spleen, and thymus. A region including the PH domain and partially overlapping with the Rho-GAP domain mediates interaction with phosphoinositides.