Transports retinoic acid to the nucleus. Regulates the access of retinoic acid to the nuclear retinoic acid receptors. Interacts with importin alpha (By similarity). Interacts with RXR and RARA. Upon ligand binding, a conformation change exposes a nuclear localization motif and the protein is transported into the nucleus. Embryo and skin of adult mouse. By retinoic acid. Forms a beta-barrel structure that accommodates hydrophobic ligands in its interior. Sumoylated in response to retinoic acid binding, sumoylation is critical for dissociation from ER and subsequent nuclear translocation. Belongs to the calycin superfamily. Fatty-acid binding protein (FABP) family.