MCF-7 cells are characterized as estrogen receptor (ER)-positive/ progesterone (PgR)-positive/ human epidermal growth factor receptor (HER2)-negative, luminal subtype, while MDA-MB468 and MDA-MB231 cells are known as triple-negative breast cancer (TNBC), ER-negative/ PgR-negative/ HER2-overexpression, basal subtype. Here, ESR1 is linked to triple-negative breast carcinoma.