As shown in Figure S1A, compared with MCF7 (ER‐positive breast cancer cell line) and MDA‐MB‐468 (GPER‐positive TNBC cell line), ERα, ERβ, and GPER were significantly either very low or not expressed in NFs, BT549, and MDA‐MB‐231 cells. This evidence concerns the gene ESR2 and breast cancer.