Rapid changes in the localization of a constitutively active kinesin during stage 2. The accumulation of constitutively active kinesin at the tip of a neurite is a measure of the efficiency with which it translocates along the microtubules in that neurite. This kinesin accumulated first in one neurite, then in another. This observation suggests that the biochemical properties of the microtubules, which regulate kinesin transport, differ in different neurites and change rapidly over time. This construct (KIF17^1–511-GFP), which includes the motor domain but lacks the autoinhibitory domain, was expressed by nucleofection before plating. One day later, its localization was imaged at 15-min intervals, then was overlaid on the corresponding phase-contrast images, which show the cell's growth. The entire sequence is shown in Movie 2. (See Movie 2.)