(A) Immunofluorescence of XPD/WT and XPD/R683W cells in anaphase overexpressing either Flag-XPD/WT, Flag-XPD/T425A, or Flag-XPD/T425D. Cells were synchronized in mitosis for 16 hours with nocodazole (100 ng/ml) and collected 90 min after nocodazole release. Immunofluorescence analyses were performed with antibodies targeting the Flag-Tag, Eg5, and α-tubulin. Chromosomes were stained with DAPI. The arrows point to mitotic spindle defects. Scale bar, 5 μm. (B) Overexpression of Flag-XPD/WT (lane 2), Flag-XPD/T425A (lane 3), and Flag-XPD/T425D (lane 4) in XPD/R683W cells were analyzed by Western blots. The level of endogenous XPD can be visualized in nontransfected XPD/R683W cells (lane 1). (C) Relative presence of Eg5 on the mitotic spindle [n = 3, means ± SD; two-tailed Student’s t test for sample 1 versus 2 and ordinary one-way analysis of variance (ANOVA) test for sample 2 versus 3, sample 2 versus 4, or sample 2 versus 5; ****P < 0.0001]. (D and E) Percentage of cells displaying mitotic spindle defects (D) and with segregation errors (E) (n = 3, means ± SD; at least 300 cells per experiment and per condition were counted; *P < 0.05, **P < 0.01, and ***P < 0.001, Student’s t test).