TUNEL assay of the fragmented DNA from apoptotic cells. Clockwise from top left: untransfected NPC-TW01 cells (blank), transfection reagent only (mock), transfection reagent and miR-1 (miR-1) and transfection reagent and miR-negative control (miR-negative). After transfection for 120 hours, the cells were subjected to TUNEL assay. TUNEL-stained cells were quantitated by flow cytometry. The number in each panel is the percentage of TUNEL-positive cells.