To evaluate whether CD137L expressed on tumor cells was functionally active, CD137L‐expressing HCC‐827 cells were cocultured with T cells in the presence or absence of soluble antihuman CD3 mAb or antihuman CD137 mAb, and the supernatant IFN‐γ concentration was then measured. This evidence concerns the gene TNFRSF9 and hepatocellular carcinoma.