In addition to ER+ MCF7 cells and ER- MDA-MB-231 cells representative of the mesenchymal stem-like subtype of triple negative breast cancer (TNBC) [48], we used two additional TNBC cell lines – HCC1806 (basal-like 2) and MDA-MB-468 (basal-like 1) – in addition to the MCF10A non-transformed mammary epithelial cell line. Here, ESR1 is linked to triple-negative breast carcinoma.