Immunofluorescence microscopy was performed as previously described61 (link),62 (link) on a Zeiss LSM710 microscope (Carl Zeiss, Thornwood, NY). Live-cell imaging was conducted with a NIKON Eclipse Ti Microscope System equipped with an environmental chamber (temperature controlled at 37°C and CO2 at 5%), high-speed EM charge-coupled device cameras (iXon DU897 from Andor and Evolve 512 from Photometrics), and NIS-Elements Ar Microscope Imaging Software. TIRF Images were acquired with an Apo TIRF 100X objective (N.A. 1.49) and iXon DU897. Spinning-disk confocal z-stacks were taken with a Plan Apo VC 60x H objective (N.A. 1.40) and Evolve 512. Dual-color imaging was achieved by fast switching excitation lasers so that images from green and red channels were aligned automatically.