Comparison of apoptosis induction by As2O3 in NB4 versus U937 cells. (A) Fluorescence microscopy determination of apoptotic cells. Cells were treated with either 0 (control), 1, or 2 μmol/L As2O3 for up to 4 days, and the number of apoptotic cells was determined by fluorescence microscopy according to the morphology. The results are expressed as the percentage of apoptotic cells in the culture. Values shown are the mean of triplicate determinations with a standard deviation of less than 10%. (B) FACS analysis of apoptotic cells. Cells were treated for 3 days with the indicated concentrations of As2O3 and then evaluated for DNA content after propidium iodide staining. (C) TUNEL assay to determine apoptotic cells. Cells were treated with As2O3 at the indicated time for 3 days.
