PTMA siRNA and miR-1 accelerate the apoptotic process in cells were treated with actinomycin D. From top to bottom: untransfected NPC-TW01 cells (blank), transfection reagent only (mock), transfection reagent and negative control siRNA (Neg-si), transfection reagent and PTMA siRNA (PTMA-si), transfection reagent and miR-negative control (miR-neg) and transfection reagent and miR-1 (miR-1). Actinomycin D apoptotic inducer was added to culture media to a final concentration of 5 μM after 48 hours of transfection. Cells were subsequently observed by time-lapse microscopy (A). The time above each photograph represents the specific time that cells were transfected with microRNA, siRNA or control. (B) Cell viability was quantitated by MTT assay. The experimental conditions of the MTT assay were identical to those during time-lapse microscopy observation. Transfection of PTMA siRNA or miR-1 accelerated the apoptotic process after the NPC-TW01 cells were treated with actinomycin D apoptotic inducer.