Confocal microscopy has been described previously26 (link). Briefly, confocal microscopy was carried out on Zeiss AxioObserver inverted microscope with either LSM780-Quasar (34-channel spectral, high-sensitivity gallium arsenide phosphide detectors, GaAsP) or LSM880 confocal module controlled by the Zen software. All live cell imaging was carried out in a temperature/humidity/CO2-regulated chamber.