Effect of EGFR siRNA transfection on the growth of the lung cancer cells. Both time-dependent and dose-dependent effects were investigated. Cells were incubated in the presence of 200 nM siRNA for 0, 24, 48, 72, and 96 h (A) and also assessed with 0, 8, 40, or 200 nM siRNA for 72 h (dose-response curves, B) using the MTS cell growth assay. Cell growth is expressed relative to the mock control group as absorbance of siRNA/mock control ×100. The average ratio was calculated from six independent wells.