Fig. 2

HF induces caspase-dependent apoptosis in K562 cells. A The nuclear changes were determined by Hoechst 33258 staining and photographed by fluorescence microscopy (× 200, scale bar = 50 μm). B The proportion of apoptotic cells treated with HF (0, 5, 10 and 20 μM) for 48 h was analyzed by flow cytometry. C The apoptosis of K562 cells pre-treated with 40 μM Z-VAD-FMK for 1 h before exposed to 10 μM HF for 48 h. D, E The expression levels of cleaved caspase-3, cleaved caspase-9 and cleaved PARP were detected by western blotting after treatment with different concentrations of HF (0, 5, 10 and 20 μM) and different times of 10 μM HF. *P < 0.05, **P < 0.01, ***P < 0.001 vs the control group