TPX2 mutants have a higher percentage of defective divisions, delayed mitoses, and increased metaphase BUB1 staining. (a) Percentage of defective mitoses in mTPX2^WT, mTPX2^AAA, and mTPX2^ΔN cells after TPX2 or CON RNAi, quantified by observing time-lapse videos of GFP fluorescence. Actual numbers of cell divisions observed are shown below the histogram. (b) mTPX2^AAA and mTPX2^ΔN cells after TPX2 RNAi show longer delays in mitosis and a higher percentage of cells exhibiting delays. Lengths of individual mitosis are plotted for mTPX2^WT, mTPX2^AAA, and mTPX2^ΔN cells after TPX2 or CON RNAi. Percentages shown are the fraction of cells showing lengths of mitoses greater than 120 min. (c) Immunofluorescence of mTPX2^WT and mTPX2^ΔN prometaphase and metaphase cells after TPX2 RNAi, stained for BUB1 or MAD2. Insets show DNA (DAPI) from the same cell at lower magnification. In mTPX2^WT cells, MAD2 and BUB1 foci are enriched in prophase but not metaphase. In mTPX2^ΔN cells, MAD2 enrichment is gone in metaphase cells, whereas some Bub1-positive foci remain. Bars, 10 μm.