ORAI1 and breast cancer: Thus, in triple negative breast cancer cells, such as MDA-MB-231 cells, SOCE has been reported to be strongly dependent on STIM1 and Orai1 [8], with TRPC6 playing a relevant role in the surface expression of Orai1 [9], while in luminal breast cancer cells SOCE is mostly mediated by STIM1, STIM2, and Orai3 [8].