Overexpression of FOXP1 leads to a decrease in PD-L1 expression in NPC and GC cells, as evidenced via qRT-PCR (Supplementary Fig. 7c), western blotting (Fig. 3c), immunofluorescence staining of HONE1 cells (Fig. 3d), and flow cytometry assays of HONE1 and HONE1-EBV cells (Fig. 3e and Supplementary Fig. 7d), whereas FOXP1 knockdown upregulated PD-L1 expression. This evidence concerns the gene FOXP1 and gastric cancer.