TIP47 has been described as cargo protein involved in the trafficking of the mannose-6-phosphate receptor between endosomes and the Golgi complex. Mannose 6-phophate receptors (MPRs) deliver lysosomal hydrolase from the Golgi to endosomes and then return to the Golgi complex. The protein encoded by this gene interacts with the cytoplasmic domains of both cation-independent and cation-dependent MPRs, and is required for endosome-to-Golgi transport. This protein also binds directly to the GTPase RAB9 (RAB9A), a member of the RAS oncogene family. The interaction with RAB9 has been shown to increase the affinity of this protein for its cargo. TIP47 has been localized in milk fat globule membranes of human and bovine origin. It has been described as a placental protein, as well. Increased amounts of TIP47 are secreted into circulation of cervix carcinoma patients. Therefore, this protein is probably significant as an oncodevelopmental marker.