Intracellular transport of retinol. Higher expression in adult kidney and liver and to a lesser extent in adult and fetal spleen, adult lymph nodes and appendix, and fetal liver and kidney. Strongly decreased in hepatocellular carcinoma tissues (at protein level). Forms a beta-barrel structure that accommodates hydrophobic ligands in its interior. Belongs to the calycin superfamily. Fatty-acid binding protein (FABP) family.