Flow cytometric analysis further confirmed that BER at concentrations of 20 μM, 40 μM, and 60 μM displayed dose-dependent induction of apoptosis in both estrogen-receptor negative and highly-metastatic human breast cancer cell line MDA-MB-231 cells, and the estrogen receptor-alpha-positive MCF-7 cells after the cells were treated for 48 h with BER. Here, ESR1 is linked to breast cancer.