FIG. 6.

Comparison of KSP-IA- and paclitaxel-induced activation of spindle checkpoint and apoptosis in cells containing wild-type or mutant p53. (A) HCT116 cells (containing wild-type p53) and MDA-MB-468 cells (containing mutant p53) were treated with vehicle or doxorubicin (200 nM) (+) for 16 h. The steady-state levels of p53 and p21 were determined by Western blotting. GAPDH was included as a loading control. The mutant p53 defective for transactivation activity was detected in MDA-MB-468 cells in the absence (−) of doxorubicin. (B and C) HCT116 and MDA-MB-468 cells were treated with KSP-IA (300 nM) or paclitaxel (100 nM) for various times and then analyzed for caspase-3 activity (caspase-3-mediated cleavage of PARP [c-PARP]), spindle checkpoint activation (p-BubR1), mitotic arrest (p-histone H3), and cellular DNA content by Western blot and FACS analyses.