Microtubule plus ends redistribute at anaphase B onset. (A and C) Distribution of the microtubule tip tracker EB1 over time in S2 cells stably expressing RFP-EB1. Time is shown in min:sec and scale bars represent 5 μm. Two different phenotypes were observed. Arrow in bottom left panel of C indicates puncta of EB1 fluorescence visible at the equator of individual MT bundles. Tight redistribution of the plus ends (A) to the equator was seen in 25% of cells. (B and D) Whole spindle kymographs demonstrating EB-1 distribution across the spindle over time.