ER-α was highly expressed in human breast and ovarian cancer cell lines (O’Donnell et al., 2005; Sotiriou and Pusztai, 2009; Miyoshi et al., 2010; Siersbæk et al., 2018), while its mRNA was not detected in human colon cancer cell lines, such as HCT8 and HCT116 (Fiorelli et al., 1999). This evidence concerns the gene ESR1 and ovarian cancer.