5-azacytidine and decitabine induce apoptosis in neoplastic MCs. (A-B) HMC-1.1 cells and HMC-1.2 cells were incubated in control medium (Co) or in medium containing various concentrations (1-20μM) of 5-azacytidine or decitabine at 37°C for 48 hours (gray bars) or 96 hours (black bars). After incubation, apoptotic cells were quantified by either light microscopy (A) or by flow cytometry using an antibody against active caspase-3 (B). Results show the percentage of apoptotic cells and active caspase-3-positive cells, and represent the mean ± SD of 5 independent experiments (*P < .05 compared with control). (C) BM-derived MCs from a patient with ASM were cultured in the presence or absence (Co) of various concentrations of 5-azacytidine or decitabine at 37°C for 48 hours (gray bars) or 96 hours (black bars). Results show the percentage of apoptotic cells determined by light microscopy.