We revealed that BC5 carcinoma cells were PGRlow/ERβhigh/ERα−/Cyp19+, BrCCh1 cells that originated from the recurrent tumour were PGR−/ERβ+/ERα−/Cyp19+, and normal BN1 cells were PGR−/ERβ+/ERα−/Cyp19high (Fig. 2a). The gene discussed is ESR1; the disease is carcinoma.