Figure 1. Expression of small interfering RNA (siRNA) against HeLa cells stably expressing green fluorescent protein (GFP), with the siRNA delivered by simian virus 40 vectors packaged in vitro (SV40-IVP-siGFPs) or by lipid transduction. The majority of SV40-IVP-siGFP cells ceased GFP production (green), while most of the cells transfected with siRNAs (siGFPs) via lipids showed much higher expression of GFP (blue). Cells were analyzed 3 days after transduction.