FIG. 1.

Bax mediates KSP-IA-induced apoptosis. (A) siRNA-mediated knockdown of Bax. Both A2780 and HCT116 cells were transfected with either the control luciferase (Luc)- or Bax-specific siRNA. Twenty-four hours after transfection, the steady-state levels of Bax were determined by Western blot analysis. Nontransfected cells (NT) were also analyzed for comparison. (B) Suppression of KSP-IA-induced apoptosis by siRNA-mediated knockdown of Bax. At 24 h after siRNA transfection, cells transfected with either the Luc or Bax siRNA and NT cells were treated with either DMSO (vehicle) or KSP-IA (300 nM) for 48 h. The extent of apoptosis was determined by FACS analysis, and the subdiploid (sub-G₁) fractions (indicative of apoptotic cells) are shown.