ORAI1 and cancer: Among the Ca2+ channels in cancer cells, Orai1, the pore-forming subunit of the Ca2+ release-activated Ca2+ (CRAC) channel [8,9], which is the best characterized store-operated Ca2+ channel, has been found to be overexpressed in the human cancer cells investigated, including breast cancer [10], melanoma [11], clear cell renal carcinoma [12] and non-small cell lung carcinoma [13], except in prostate cancer cells, whose expression has been reported to be reduced as compared to normal tissue [14].