13-cis Retinoic acid exerts its specific activity on human sebocytes through selective intracellular isomerization to all-trans retinoic acid and binding to retinoid acid receptors. - Tsukada,M.; Schroder,M.; Roos,TC.; Chandraratna,RA.; Reichert,U.; Merk,HF.; Orfanos,CE.; Zouboulis,CC. (J Invest Dermatol, 2000)