This in vitro study investigated the influence of a 17-beta estradiol analogue, EMBS, on proliferation, cell cycle progression and apoptosis induction in an adenocarcinoma receptor positive cell line (MCF-7), estrogen receptor-negative metastatic cell line (MDA-MB-231) and a non-tumorigenic epithelial breast cell line (MCF-12A). Here, ESR1 is linked to adenocarcinoma.