Overview of RA metabolism and signaling. Dietary vitamin A is converted into retinal via alcohol dehydrogenase (ADHs) or short-chain dehydrogenase/reductase (SDRs) and then oxidized to RA by the RALDHs. RA acts by binding the nuclear receptors RAR and RXR to form a transcriptional complex with additional cofactors (CF; which may include NFATc2) that drives the transcription of RARE-containing genes.