Plays a role in apical endocytosis/recycling. Plays a role in the maturation and acidification of phagosomes that engulf pathogens, such as S.aureus and M.tuberculosis. Plays a role in the fusion of phagosomes with lysosomes. Highly enriched on apical endocytic structures in polarized epithelial cells of kidney proximal tubules (By similarity). Recruited to phagosomes containing S.aureus or M.tuberculosis (PubMed:21255211). Low or absent expression in normal pancreas and stronger expression in 15 of 18 exocrine pancreatic adenocarcinomas (at protein level). Belongs to the small GTPase superfamily. Rab family.