STIM1 and breast cancer: We also examined the expression of STIM2 and STIM1 in a panel of breast cancer cell lines and found a higher level of STIM2 in two mesenchymal-like cell lines (MDA-MB-231, BT-549) than in three epithelial-like cell lines (T-47D, BT-474, and MCF7) (Fig. 2d–f).