AGN 195183 is a potent and selective agonist of RARα(Kd=3 nM) with improved binding selectivity relative to AGN 193836; no activity on RARβ/γ. IC50 value: 3 nM (Kd); 200 nM (EC80, RAR Trans.) Target: RARα agonist Compound 4(AGN-195183) inhibited the growth of breast cancer cell lines, and was inactive in an in vivo model of topical irritation. Compound 4 and ATRA inhibit growth of the human breast cancer cell lines, T-47D and SK-BR-3, compound 4 does not cause the topical irritation induced by the RARa-selective retinoid, Am-580. Compound 4 (AGN 195183) is currently in Phase I/IIA clinical trials in cancer patients.