ESR1 and breast carcinoma: Positivity was observed in the cytoplasm of PMC42 (Fig. 1C), MCF7 (Fig. 1D) both ER positive and SKBR3 HER2 positive (Fig. 1E) breast cancer cell lines, while MDA-MB-231 (Fig. 1F) and MDA-MB-436 (Fig. 1G), triple negative, breast cancer cell lines showed no signal.