The apoptotic effect induced by HPB242 in HN22 and HSC4 cells. Cells were incubated with HPB242 (5, 10, and 20 μg/ml) and untreated for 48 hours. The cells were harvested and prepared for DAPI staining and PI staining as described in the Methods section. (A) Analysis of DNA fragmentation and nuclear condensation by fluorescence microscopy (magnification ×600) after HPB242 treatment in HN22 and HSC4 cells. (B) DNA fragmentation and nuclear condensation were quantified, and the results in triplicate are expressed as the mean ± SD. (C and D) Representative histograms of Sub-G1 population. HPB242-treated cells were compared with untreated cells, and data are shown as the average of triplicate samples from three independent experiments. The asterisks (*) indicates p < 0.05 versus control cells.