ORAI1 and breast carcinoma: In naïve cells, with a normal AC8 expression, AC8 is expected to promote inactivation of a large subset of Orai1 channels; however, in breast cancer MDA-MB-231 cells, which predominantly overexpress AC8 over Orai1, the AC8/Orai1 stoichiometry is shifted in favor of AC8 and, subsequently, the subset of AC8-independent Orai1 is expected to be reduced, and the AC8-induced Orai1 inactivation is, thus, impaired (Figure 12).