The GAS5 expression in lung adenocarcinoma cell line and the effect of gefitinib combined with GAS5 on the proliferation of A549 cell line (A) qRT-PCR results demonstrating GAS5 expression in NSCLC cell lines (A549, H1650, H1975, HCC827) compared to human bronchial epithelial cells (HBEs). (B) IC50 of four NSCLC cell lines. (C) GAS5 expression, measured by qRT-PCR, following the treatment of A549 cell line with pCDNA-GAS5 or empty vector. (D) The effect of GAS5 plus gefitinib on A549 proliferation in vitro. MTT assay was performed to determine the proliferation of pCDNA-GAS5- or empty vector-transfected A549 cells plus gefitinib.