Rabbit Anti-Human RORB polyclonal antibody for IHC-P. Retinoids are metabolites of vitamin A (retinal) and are believed to represent important signaling molecules during vertebrate development and tissue differentiation. Two families of retinoid receptors have been identified. Retinoic acid receptors (RARs) include RARalpha, RARBeta and RARgamma, each of which has a high affinity for all-trans retinoic acids and belong to the same class of nuclear transcription factors as thyroid hormone receptors, vitamin D3 receptor and ecdysone receptor. The ligand binding domains of the RARs are highly conserved and RAR isoforms are expressed in distinct patterns throught development and in the mature organism. Members of the retinoid X receptor (RXR) family, RXRalpha, RXRBeta and RXRgamma, are activated by 9-cis-retinoic acid, a stereo- and photoisomer of all-trans-RA that is expressed in vivo in both liver and kidney and may represent a widely used hormone. ****