Involved in the metabolism of retinoic acid (RA), rendering this classical morphogen inactive through oxidation (PubMed:15661642). Appears to be involved in the inactivation of all-trans-retinoic acid (RA) (PubMed:15661642). Plays a role in skeletal development (PubMed:22019272). all-trans-retinoate + O2 + reduced [NADPH--hemoprotein reductase] = all-trans-4-hydroxyretinoate + H(+) + H2O + oxidized [NADPH--hemoprotein reductase] Expressed zygotically. Weak expression at 75% epiboly. At the 2-somite stage, expressed in the presumptive rhombomere 4 (r4) region partially overlapping with the r3 region. At the 10-somite stage, expressed in the r4, r3 and r2 regions. At the 14-somite stage, expression extends to the r5 and r6 regions and is observed in the diencephalon. At 24-48 hours post-fertilization (hpf), additionally expressed in the eye, midbrain-hindbrain boundary, cerebellum, pectoral fin and the pharyngeal arch primordia. Belongs to the cytochrome P450 family.