PGP and lung cancer: This study aims to (1) detect P-gp expression in NSCLC tissues and cell lines and study its biological effects through a series of in vitro and in vivo experiments, (2) evaluate the cytotoxicity of Ad-VT on lung cancer cells in vitro, (3) investigate the mechanism of Ad-VT in chemotherapy-resistant lung cancer cells, and (4) determine the therapeutic effect of Ad-VT combined with gemcitabine or paclitaxel in an in vivo lung tumor model.