Figure 1. Characteristics of post-slippage multinucleation and apoptosis in response to anti-mitotic drugs. (A) Phase-contrast images of post-slippage U-2 OS cells treated with 150 nmol/L paclitaxel (Ptx), 150 nmol/L paclitaxel + K5 siRNA, and 1 μmol/L Kinesin-5 inhibitor (K5I), respectively. (B) Average number of post-slippage nuclei per cell (± SD) and (C) cumulative survival curves of U-2 OS cells under the indicated siRNA treatments in combination with 150 nmol/L paclitaxel or under treatment of K5I alone. Total number of cells analyzed for each condition ranges from 70–75. *P < 0.05 vs. Ctrl (no siRNA). Individual cells were monitored by time-lapse microscopy, and time from mitotic slippage to morphological death was measured and plotted as cumulative survival curves. (D) Knockdown of Kinesin-5 (K5) attenuated post-slippage apoptosis (indicated by Parp1 cleavage) and DNA damage (indicated by γH2A.X) induced by paclitaxel.