To examine the impact of colitis on RA signaling, we studied the expression of Aldh1a1 (aldehyde dehydrogenase 1 family member A1), Cyp26a1 (cytochrome P450 family 26 subfamily A member 1), Cyp26b1 (cytochrome P450 family 26 subfamily B member 1), RA transport Rbp4 (retinol binding protein 4), Crabp1 (cellular retinoic acid binding protein 1), Crbp1 (cellular retinol binding protein 1), and RA receptor Rarβ (retinoic acid receptor beta). The gene discussed is RBP1; the disease is colitis.