RAR/RXR 

The retinoic acid receptor (RAR) and the retinoid X receptor (RXR) are nuclear receptor which can also act as a ligand-activated transcription factor that is activated by both all-trans retinoic acid and 9-cis retinoic acid, retinoid active derivatives of Vitamin A. As with other type II nuclear receptors, RAR heterodimerizes with RXR and in the absence of ligand, the RAR/RXR dimer binds to hormone response elements known as retinoic acid response elements (RAREs) complexed with corepressor protein. Due to RAR/RXR heterodimers acting as subtrates to the non steroid hormone ligand retinoid they are extensively involved in cell differentiation, proliferation, and apoptosis.