Required for KRAS signaling regulation and modulation of cell proliferation (By similarity). Regulator of KRAS prenylation, and probably prenylation of other small GTPases (By similarity). Required for lymphocyte development and function (By similarity). Not required for myeloid cell development (By similarity). Homodimer (By similarity). Interacts with GPR89; the interaction stabilizes GPR89 (By similarity). Interacts with RAP1GDS1 (By similarity). Belongs to the small GTPase superfamily. Rab family.