Increased apoptosis in Ubp43 shRNA–expressing KT-1 cells treated with IFN. KT-1 cells stably transduced with the control or Ubp43 shRNA was treated with (A) 1000 units/mL or (B) 100 units/mL hIFNα, and the percentage increase in apoptotic cells (over untreated cells) was determined by annexin V/7-AAD staining at various time points. The apoptotic percentage represents the sum of early (annexin V positive) and late (annexin V/7-AAD double positive) apoptotic percentages. The results are the mean ± SD of 3 separate experiments. A comparison of the apoptotic percentage at 72 hours in control shRNA–expressing cells to that of UBP43 shRNA–expressing cells yields P values of (A) .05 and (B) .02. (C) KT-1 cells expressing the various shRNAs were treated with 1000 units/mL hIFNα. Western blots of the lysates at various time points were probed with anti–cytochrome c, anti-TRAIL, or anti–caspase 3 antibodies. Ponceau stains of the blots are shown as protein loading controls.