ROC curves for distinguishing Ca 2+ -treated versus non-treated cell populations based on CaST non-IRES cells from c ( i ; AUC = 0.87, P = 2.0 10 - 85 , Wilson/Brown method) and CaST-IRES-transfected cells from g ( j ; AUC = 0.93, P = 3.1 10 - 77 , Wilson/Brown method). All scale bars, 300 m. **** P < 0.0001.