Cells were incubated with 2 μM Fluo-4AM (Molecular Probes) and 0.02% Pluronic F 127 detergent in Krebs HEPES buffer (KHB). Time-lapse image sequences (×40 magnification) were acquired at 0.9 Hz and analyzed by FluoroSNNAP software operated by MATLAB. For a detailed protocol see Supplemental Experimental Procedures.
