RAR gamma
Retinoic acid receptor gamma, from the RARG gene, is the dominant RAR subtype in skin, where it mediates most retinoid actions on keratinocyte differentiation and is a principal target of topical agents such as tazarotene. Like RAR alpha and RAR beta it heterodimerizes with RXR and binds retinoic acid response elements, but its expression pattern skews toward epithelia, cartilage and certain hematopoietic lineages. During development RAR gamma patterns the vertebral column and limb bud, and redundancy among RAR subtypes explains the milder single-knockout phenotypes. In cancer, RARG is overexpressed in some hepatocellular and ovarian tumors and has been implicated in leukemia stem cell maintenance, while RARG rearrangements occur in rare lymphomas, making it a marker of subtype-selective retinoid development.
