Annexin-V binding: HUT-102 cells were treated for 48 hours or 72 hours with As (1 mmol/L), IFN (1,000 U/mL), or their combination. Using FITC-conjugated Annexin-V membrane staining and PI nuclear counterstaining, the relative amount of apoptotic cells (FITC⁺ PI⁻) and dead cells either necrotic or postapoptotic (FITC⁺ PI⁺) was determined. The percentage of dead cells is relative to the total cell population, while the percentage of apoptotic cells is presented with regard to the PI⁻, ie, nondead cells. (□), Apoptotic; (▪), dead. Fluorescence microscopy analysis showed the presence of apoptotic cells (small arrows) and dead cells (large arrows).