Cytotoxicity of agents analyzed by FACS. Results for the comparative analysis of the effects of zebularine (A) and 5-azacytidine (B). FL1-Height and FL2-Height represent Annexin V-staining and PI staining, respectively. Untreated control cell populations of DU145 and Huh-7 cells consist of a major portion of viable cells (> 90%). This reference profile changes with treatment of cells with different drug concentrations applied for 72 hrs. The viability of cells was normalized against the viability in the control population (considered as 100%) and displayed as a chart for zebularine (C) and 5-azacytidine (D).