As Orai1 is highly expressed, at the transcript and protein level, in breast cancer cells, with the exception of SKBR3, where we have found overexpression of the Orai1 mRNA but normal Orai1 protein expression (see Fig. 1), we have investigated the functional role of Orai1 in the mammosphere formation efficiency in BCSC derived from these cells as compared to BSC isolated from the MCF10A breast epithelial cell line. The gene discussed is ORAI1; the disease is breast cancer.