Effect of NK314 on cell cycle and apoptosis in ATL cell lines. (A) Cell-cycle analysis using flow cytometry after NK314 treatment of ATL cells. ATL cells were treated with the indicated concentrations of NK314 and then fixed and stained with propidium iodide 24 hours after treatment. Cellular DNA content and cell cycle profiles were determined with CellQuest software Version 3.1 (BD Biosciences). (B) Annexin V and propidium iodide analysis of ATL cells treated with NK314. Cells treated with NK-314 for 24 hours were simultaneously stained with annexin V and propidium iodide according to the manufacturer's instructions. Stained cells were conducted to a fluorescence-activated cell sorter analysis to determine the number of apoptotic cells. The ratio of apoptotic cells was calculated as number of apoptotic cells treated with NK314 of the indicated concentrations divided by the number of untreated cells and expressed as mean ± SD of triplicate analyses.