SiRNA-mediated RNAi effects in A549 and SPC-A1 cells. (A) dsRNA-mediated inhibition of EGFR gene expression in A549 cells (upper) and SPC-A1 cells (lower). Fluorescence images taken 48 h after transfection were shown. (a) Cells were stained with FITC-conjugated secondary antibody. (b) Cells were stained with an EGFR-specific antibody and secondary antibody. (c) FITC staining of cells transfected with unrelated dsRNA. (d) FITC staining of cells transfected with dsRNA-EGFR. (B) EGFR gene expression was quantified in both control and transfected cells by a flow cytometry with excitation and emission settings of 488 nm and 530 nm respectively. Cells were transfected for 48 h, then stained with an EGFR-specific antibody. Results were expressed as the percentage of fluorescent intensity relative to controls. Each column represented the mean of three replicated experiments. (C) EGFR gene level was quantified by real-time PCR. Expression of EGFR mRNA was analyzed using a semiquantitative real-time PCR assay. The relative gene levels were calculated in relation to the expression of the housekeeping GAPDH gene.