Effect of ABL-N on cell cycle progression and apoptosis in breast cancer cells. After treatment with 20 μM ABL-N for indicated times, MDA-MB-231 cells were harvested. (a) The percentage of cell cycle distribution for cells done in triplicate with similar results. (b) Nuclear condensation was shown by DAPI-staining assay (magnification, ×100). (c) DNA fragmentation was evaluated using a Cell Death Detection ELISAPlus kit. The data are expressed as means ± SE of three separate experiments.*P <0.05, **P <0.01, as compared with the group without ABL-N treatment. (d) The apoptotic status was determined by Annexin V/PI staining method. Percentages of negative (viable) cells, annexin V-positive (early apoptotic) cells, PI-positive (necrotic) cells, or annexin V and PI double-positive (late apoptotic) cells were shown (mean of three independent experiments) by a flow cytometric analysis.