ORAI1 and breast cancer: Orai3 contributes to the SOCE in luminal cells expressing estrogen receptors (ER+) such as MCF-7 and T47D cell lines, but not in the estrogen-negative (ER−) basal cells such as MDA-MB-231 [24], while Orai1 mediates SOCE in basal-like BC cell lines [22,24].