Figure 1

shRNA-mediated RNAi silencing in HEK293T cells by P19, Tat, VP35 or 45R. HEK293T cells were transfected with expression plasmids for firefly (Fluc) and Renilla luciferase (Rluc) together with a shRNA that targets Fluc (sh-Fluc, lanes 2–17) or a control irrelevant shRNA (shGFP, lane 1). As indicated, increasing amounts of expression plasmids for GFP, FLAG-tagged P19, Tat, VP35 or 45R (45 repeated arginines) were also co-transfected into HEK293T cells. Luciferase activities were quantified at 20 hours post transfection, and Fluc/Rluc ratios are graphed based on the averages from three independent experiments.