MCF-7, T-47D and ZR-75-1 are luminal breast cancer lines, SKBR-3 and MDA-MB-453 are ER− but express FOXA1 and AR and are representative of the mApo subtype, with ERBB2-amplification and high expression in SKBR-3 and MDA-MB-453, respectively. The gene discussed is ERBB2; the disease is breast cancer.