ChEBI: All-trans-retinoic acid is a retinoic acid in which all four exocyclic double bonds have E- (trans-) geometry. It has a role as a keratolytic drug, an antineoplastic agent, an antioxidant, a signalling molecule, a retinoid X receptor agonist, an anti-inflammatory agent, an AP-1 antagonist, a retinoic acid receptor agonist and a human metabolite. It is a conjugate acid of an all-trans-retinoate.NCI Thesaurus (NCIt): Tretinoin is a naturally-occurring acid of retinol. Tretinoin binds to and activates retinoic acid receptors (RARs), thereby inducing changes in gene expression that lead to cell differentiation, decreased cell proliferation, and inhibition of tumorigenesis. This agent also inhibits telomerase, resulting in telomere shortening and eventual apoptosis of some tumor cell types. The oral form of tretinoin has teratogenic and embryotoxic properties.