Figure 1. Schematic representation of the intracellular retinoid signaling pathway

Retinol is converted into retinal and retinoic acids, before either it acts through nuclear retinoid receptors or is inactivated by hydroxylation. Abbreviations are: ADH: alcohol dehydrogenase; CRABP: cellular retinoic acid binding protein; CRBP: cellular retinol binding protein; CYP26: cytochrome p450 retinoic acid inducible; RAR: retinoic acid receptor; RALDH: retinaldehyde dehydrogenase; RXR: retinoid X receptor, SDR: short-chain dehydrogenase/reductase.