ESR1 and breast carcinoma: b Common breast cancer subtype-marker expression in representative Her-2 positive (Her-2+), luminal A (ER/PR+, Her-2-, EGFR-, Ki-67% < 14%), luminal B (ER/PR+, Her-2-, EGFR-, Ki-67% ≥ 15%), and BLBC (ER-, Her-2-, EGFR+, CK5/6+) tissues by IHC (Red scale bar = 200 μm; Purple scale bar = 40 μm).