Effect of SET down-modulation on granzyme B expression in IL-15– or IL-2–activated human NK cells. pSUPER-infected and pSUPER.retro-shSET-infected NK-92 cells starved from IL-2 were left untreated or stimulated with IL-15 (100 ng/mL) or IL-2 (15 ng/mL) for 18 hours. Cells were analyzed for granzyme B, SET and actin protein levels by Western blot (A), and granzyme B transcript level by real-time RT-PCR (B; n = 4). *^,**P < .01. Each experiment is representative of at least 3 performed with similar results.