FIGURE 2.

MCAK depletion increases astral microtubule density and increases the frequency of lagging chromosomes. Wild-type CHO cells were transfected with the empty vector (Control) or with the same vector engineered to express shRNA for MCAK. A, after 24 h, the cells were stained with an antibody to α-tubulin. Metaphase spindles are shown. Cells transfected with shRNA produced mitotic spindles that had a greater abundance of astral fibers that were, on average, 1.5–2-fold longer than their normal counterparts. The insets show 2-fold enlargements of the area around one spindle pole. B, cellular DNA stained with DAPI. Chromosomes that appeared to lack a connection to the spindle poles, did not segregate with the others during anaphase, or remained apart from the others during telophase (arrow) were scored as lagging chromosomes. Scale bar = 10 μm. C, the percentage of transfected mitotic cells having hairy spindles and lagging chromosomes was determined in three independent experiments and plotted. **, p < 0.005.