TNFRSF9 and hereditary clear cell renal cell carcinoma: However, TIL expansion in vitro from 16 cases of renal cell carcinoma revealed that, although TILs cultured with autologous tumor single cell suspensions could express a high percentage of CD137, only a small percentage of these cells expressed IFN-γ, TNFα and IL-2 detected by flow cytometry, suggesting that the tumor-specific CD137+ T cell subpopulation might lack tumor responsiveness to some extent (81).