Temperature measurement for the ER in HeLa cells on EuTTA nanosheets upon ionomycin treatment. (A) Time course of changes in Fluo4 F.I. (B) Same as in A for ER thermo yellow F.I. Gray lines, data in individual cells; red line, averaged data. Number of cells, 12 (n = 3). In each graph, a horizontal black line indicates the period of ionomycin treatment (2 µM, 0.1% DMSO). (C and D) Same as in A and B, respectively, but with 0.1% DMSO (no ionomycin). Number of cells, 8 (n = 2). (E and F) Same as in A and B, respectively, but both ionomycin (2 µM, 0.1% DMSO) and 0.1% DMSO were added (total 0.2% DMSO). See Materials and methods for the details. Number of cells, 12 (n = 3). (G and H) Same as in A and B, respectively, but both ionomycin (2 µM, 0.1% DMSO) and thapsigargin (2 µM, 0.1% DMSO) were added (total 0.2% DMSO). Number of cells, 13 (n = 3).