a–d GSEA analysis was performed using TCGA_LUAD, GSE31210, GSE68465, and GSE13213 databases to compare the high and low expression of GPI, respectively. e The protein expression level of GPI in normal lung tissues and indicated cell lines was analyzed by western blot. f, g The effect of GPI knockdown on the proliferation of A549 and H1299 cells was assessed by colony formation assay. h, i The effect of GPI knockdown on the migration of A549 and H1299 cells was examined by wound-healing assay (scale bar, 100 μm). j GPI knockdown inhibited tumor cells’ lung metastasis in vivo. Each group was assigned five mice, and the metastatic tumor lesion in each mouse lung was analyzed by Haematoxylin and eosin staining (H&E staining). Appearance and representative images of H&E-stained sections of the lung tissues were shown. The nodule numbers of A549/shNC and A549/sh1GPI groups were 42.2 ± 11.9 and 7.4 ± 3.5. k Western blot analysis of indicated protein expression level. GSEA, Gene Set Enrichment Analysis. The experiments were conducted in triplicate, ensuring independent replication.