Consistently, SALL2 expression in ER‐positive breast cancer cell lines, including MCF7, T47D, ZR‐75‐1, MDA‐MB‐361, MDA‐MB‐415, and ZR‐75‐30, was significantly higher than that in ER‐negative breast cancer cell lines (BT‐20, BT‐549, and MDA‐MB‐231) and in normal immortalized mammary epithelial cell lines MCF10A and MCF12A, which are also ER‐negative (Appendix Fig S3C). The gene discussed is ESR1; the disease is breast cancer.