Figure 1. Cell proliferation is significantly decreased by silencing Rac1 expression in NSCLC cell lines. (A) To assess the silencing of Rac1 expression in NSCLC cell lines, NCI-H1703 and A549 cells were either subjected to mock transfection without siRNA (lane 1) or transfected with nontargeting (NT) siRNA (lane 2) or the indicated Rac1 siRNAs (lanes 3 and 4). Cell lysates were prepared and subjected to ECL-Western blotting using antibodies to GAPDH and Rac1. Results are representative of three independent experiments. (B) Quantitative densitometry was conducted to determine the protein levels of Rac1 in the ECL-Western blots described in A. The values are normalized to densitometric values obtained from ECL-Western blots of cells subjected to NT siRNA transfection. Results are the mean ± SE from three independent experiments. (C) Cell proliferation was assayed by measuring [³H]thymidine uptake 72 h after transfecting the cells with 25 nM of the indicated siRNAs. The values are normalized to [³H]thymidine uptake by cells subjected to NT siRNA transfection. Results are the mean ± SE from three independent experiments conducted with six replicates for each treatment in each experiment. (D) Cell proliferation rate was assayed by measuring [³H]thymidine uptake at the indicated time points 72 h after transfecting the cells with 25 nM of the indicated siRNAs. Results are the mean ± SE from three independent experiments conducted with four replicates for each treatment, in each experiment. Symbols above a column indicate a statistical comparison between the indicated sample and the control sample of cells transfected with NT siRNA (*, p < 0.01)