Required for KRAS signaling regulation and modulation of cell proliferation (PubMed:31406347). Regulator of KRAS prenylation, and probably prenylation of other small GTPases (By similarity). Required for lymphocyte development and function (PubMed:32220963). Not required for myeloid cell development (PubMed:32220963). Homodimer (PubMed:32220963). Interacts with GPR89; the interaction stabilizes GPR89 (PubMed:32220963). Interacts with RAP1GDS1 (By similarity). Embryonic lethal. Belongs to the small GTPase superfamily. Rab family.