VPS9D1-AS1 knockdown inhibits proliferation, colony-forming capacity, migration, and invasiveness of H460 and A549 cells but promotes their apoptosis. (A) Evaluation of the transfection efficiency of H460 and A549 cells with si-VPS9D1-AS1 or si-NC at ~48 h post-transfection using RT-qPCR. *P < 0.05 vs. the si-NC group. (B–D) Differences in the proliferation, colony-forming capacity, and apoptosis rate of H460 and A549 cells transfected with si-VPS9D1-AS1 or si-NC determined by the CCK-8 assay, the colony formation assay, and flow cytometry, respectively. *P < 0.05 vs. the si-NC group. (E, F) Effects of treatment with si-VPS9D1-AS1 or si-NC on the migration and invasiveness of H460 and A549 cells assessed by the Transwell migration and invasiveness assays, respectively. *P < 0.05 vs. the si-NC group.