In an ex vivo tumor-infiltrating lymphocytes (TILs) stimulation assay with autologous tumor cells, CD137+ TILs exhibited the greatest frequency among the effector cells expressing IFN-γ, TNF-α, Granzyme B, perforin, and IL-2, compared to OX40+, PD-1+, CD25+, and CD69+ TILs, suggesting that CD137+ TILs might have the most effective antitumor activities. The gene discussed is PRF1; the disease is neoplasm.