ORAI1 and breast cancer: To investigate the possible functional role of Orai1 and STIM proteins N-linked glycosylation in breast cancer cells, we treated cells with tunicamycin, a nucleoside antibiotic that inhibits the initial step of N-linked glycosylation by preventing the transfer of N-acetylglucosamine-1-phosphate from UDP-GlcNAc to dolichol-P [44].