To ascertain the role of PD-L1 in immune evasion induced by TGF-β, the activity, and cytotoxicity of NK cells were determined in an in vitro assay in which NK-92 cells were cocultured with tumor cells with or without TGF-β treatment in the presence or absence of PD-1/PD-L1 inhibitor 3. This evidence concerns the gene TGFB1 and neoplasm.