Cell culture MCF7 (HTB-22), ZR-75-1 (CRL-1500), CAMA-1 (HTB-21), MDA-MB-453 (HTB-131), MDA-MB-231 (HTB-26), OVCAR-3 (HTB-161) and Kuramochi (JCRB0098) cells were obtained from the American Type Culture Collection. MCF7 ESR1Y537S cells were provided by S. Chandarlaparty35. MCF7, ZR-75-1, MDA-MB-231 and CAMA-1 cells were cultured in RPMI-1640 medium (11875-093, Gibco) supplemented with 10% fetal bovine serum (FBS; SH30054.03,