To explore differences in how breast cancer cells respond to LXR stimulation by synthetic and endogenous ligands, we generated LXRA-regulated luciferase reporter cell lines representing ER-negative (MDA-MB-468, MDA-MB-231) and ER-positive (MCF7, T47D) BCa, as well as a control liver cell line (HEPG2). The gene discussed is ESR1; the disease is breast carcinoma.