In this in vitro study, we sought to explore the potential utility of the phytochemical AM as a co-adjuvant to conventional hormonal therapy, specifically by examining the pharmacological interaction between AM and 4-OH-TMX in two ER+ breast cancer cell lines, MCF-7 and T-47D, as well as in the endometrial cell line N30. The gene discussed is ESR1; the disease is breast carcinoma.