TGFB1 and Hepatic fibrosis: For instance, it was revealed that ATRA inhibited TGF-β–induced liver fibrosis by down-regulating the collagen 1A2 gene [14] and that 9-Cis-retinoic acid, an isomer of ATRA, attenuated TGF-β–induced fibrotic changes of human mesangial cells [13].