Dose response of siGFP packaged in vitro against HeLa cells stably expressing GFP. HeLa cells stably expressing GFP (red), were transduced with a mix of packaged siGFP IVP-siRNAs-1 and IVP-siRNA-2. The in vitro packaging reaction was prepared with different concentrations of the siGFP: 1 μg (green), 10 μg (light blue), 25 μg (orange), 50 μg (dark blue), 100 μg (yellow). Transducing with IVP containing these various concentrations resulted in complete elimination of GFP expression. Cells were analyzed three days post-transduction. The right side of the FACS figure is enlarged to better display the slight differences in efficiency of the various siGFP concentrations.