ABT-869 induces apoptosis of MV-411 cells. (A) MV-4-11 cells were treated for 72 hours with ABT-869, stained with propidium iodide (50 mg/mL), and analyzed on a FACS Calibur flow cytometer. Sub-G₀/G₁ population was determined by CellQuest software and designated as apoptotic cells (% apoptotic cells ± SEM). (B) MV-4-11 cells (1 × 10⁶) were harvested at 48 hours after treatment with various drug concentrations. Cells were stained with anti–annexin V–FITC antibody and propidium iodide and analyzed by flow cytometry. Increase in apoptosis was observed with increasing concentrations of ABT-869. Percentages in bottom right quadrants are cells in early apoptosis; annexin V+ and PI−. Percentages in bottom right quadrants are cells in late apoptosis: annexin V+ and PI−. (C) Western blot analysis for PARP cleavage and caspase-3 to assess apoptosis. (D) Representative Western blot analysis of caspase-3 and caspase-9 activation and PARP cleavage in MOLM-13 cells treated with ABT-869. The results from 3 independent experiments show decrease in pro–caspase-3 levels and cleavage of PARP with increasing concentrations of ABT-869.