ESR1 and breast cancer: Consistent with previous studies [3,6], Western blot analysis of whole-cell lysates from the non-tumoral breast epithelial MCF10A cell line and the estrogen receptor positive (ER+) and TNBC cell lines MCF7 and MDA-MB-231, respectively, with a specific anti-human Orai1 antibody revealed a low expression of Orai1 in MCF10A cells and a significantly higher expression of this protein in breast cancer cells (Figure 1a,b; p < 0.05; n = 6).