AGN 193109 is a potent antagonist of retinoic acid receptors (RARs; Kd= 2, 2, and 3 nM for RARα, β, and γ, respectively), exhibiting selectivity for RARs over retinoid X receptors (RXRs; Kd= >10,000 nM for human RXRα, β, and γ receptors). This compound effectively reverses cellular morphology changes and growth suppression induced by RAR agonists such as all-trans-RA, 13-cis-RA, and 9-cis-RA in ECE16-1 human endometrial ectocervical epithelial cells, particularly when used at a 10-fold molar excess. Furthermore, AGN 193109 downregulates the expression of cytokeratin K5-8, 13, 14, 16, 17, and 19 genes, indicating inhibition of retinoid action, specifically when co-administered with TTNPB but not as a standalone treatment. In vivo studies demonstrate teratogenic effects, including cleft palate, frontonasal dysplasia, and eye malformations in mouse fetuses following a single oral dose of 1 mg/kg.