CRABP1 is a specific binding protein for a vitamin A family member. It is thought that CRABP1 plays an important role in retinoic acid-mediated differentiation and proliferation processes. CRABP1 is structurally similar to the cellular retinol-binding proteins, but binds only retinoic acid at specific sites within the nucleus, which may contribute to vitamin A-directed differentiation in epithelial tissue. It forms a beta-barrel structure which accommodates hydrophobic ligands in its interior.