ESR1 and breast cancer: In those studies, we used a mouse monoclonal antibody directed against recombinant human ERα; the epitope for this antibody was not defined, but it recognised a protein of 66 kDa (consistent with full-length wild-type ERα) in breast cancer cell homogenates detected by western blot (Chantalat et al., 2016) and detected ERα in both stromal and epithelial cells by immunohistochemistry (Bombail et al., 2008).