Loss of Oct4 or KPNA2 expression inhibits proliferation in tumor cells. Expression levels of Oct4 and KPNA2 were analyzed by western blotting in a panel of lung cancer cell lines (A). Each bar represents the mean ± SD of three independent experiments. A549 and SPC cells were treated with Oct4- or KPNA2-specific siRNAs for 72 h. Western blot of Oct4 and KPNA2 depletion efficiency in A549 and SPC cell lines (B). Cell growth rate was determined by the CCK-8 assay, as described in Section 2. The data are mean ± SD of three independent experiments (C). (Upper panel) A549 and SPC cells transduced with siRNAs for control, Oct4, or KPNA2 were subjected to a colony formation assay. (Lower panel) Histogram quantification (D). Error bars indicate ± SD.*P < 0.05, **P < 0.01.