Live imaging was performed with either a Leica SP2 inverted confocal microscope equipped with a × 40/1.25 NA oil objective with PL APO correction, a Zeiss LSM880 inverted confocal microscope equipped with a x 40/ 1.30 NA oil Ph3 M27 objective or a Zeiss LSM5 Exciter AxioObserver equipped with an EC Plan-NeoFluar × 40/1.30 oil lens. Z-series were acquired using 1 μm z-sectioning.