Depletion of TPX2 from cells results in a spindle defect phenotype distinct from TPX2 mutants or Aurora A depletion. (a) Distances between spindle poles were measured in three dimensions from live-cell image stacks taken at 3-min intervals of U2OS cells stably transfected with α-tubulin–mCherry after treatment with CON, TPX2, or AurA siRNA. Thick lines represent means and thin lines represent individual videos. The dashed line represents data from Fig. 4 for reference. (b) Representative still images from time-lapse recordings quantified in a. The cells shown transfected with CON or AurA siRNAs completed mitosis and divided, whereas the cell depleted of TPX2 arrested in mitosis for several hours and displayed fragmented spindle poles. Bar, 10 μm.