Figure 10. Bipolar spindle formation is delayed in PPP6C-depleted cells. (A) HeLa cells were transfected with control and PPP6C siRNA duplexes for 48 h and then arrested overnight with S-trityl-l -cysteine to inhibit Eg5. The drug was washed out with fresh medium, and the cells were fixed at the time points indicated. Cells were stained with DAPI, tubulin (Tub), and pericentrin (Pctn) antibodies. Arrows mark the positions of pericentrin-positive centriole structures. Bar, 10 µm. (B) The spindle and chromosome alignment status of control and PPP6C-depleted cells was counted at the times indicated and is plotted in the graph (n = 4). Error bars indicate the standard error of the mean. 1328 JCB • VOLUME 191 • NUMBER 7 • 2010