Description_x000D_ Biochem/physiol Actions_x000D_ AGN 193109 is an orally active retinoic acid receptor (RAR) antagonist that targets all three RAR subtypes with higher affinity (RARα/β/γ Kd = 2 nM) than all-trans retinoic acid/ATRA (RARα/β/γ Kd = 9/12/19 nM). AGN 193109 potently antagonizes against ATRA-induced transcription in RARα, RARβ, and RARγ transfected CV-1 cells (by 85%, 62%, and 100%, respectively, by equal molar AGN 193109 against ATRA). AGN 193109 is also widely employeed to block RAR-mediated physiological and pathalogical processes in mice and rats in vivo via oral (1-10 mg/kg) or topical (0.3-36 μmol/kg) administration.