Protein transport (By similarity). Probably involved in vesicular traffic (By similarity). GTP + H2O = GDP + H(+) + phosphate Regulated by guanine nucleotide exchange factors (GEFs) which promote the exchange of bound GDP for free GTP. Binds EEA1. Interacts with RIN2 and RIN3, which probably regulate its pathway, possibly by acting as GEFs (By similarity). Interacts with GDI1, GDI2, CHML and CHM; phosphorylation at Ser-84 disrupts this interaction (By similarity). Phosphorylation of Ser-84 in the switch II region by LRRK2 prevents the association of RAB regulatory proteins, including CHM, CHML and RAB GDP dissociation inhibitors GDI1 and GDI2. Belongs to the small GTPase superfamily. Rab family.