As expected, baseline CD137 expression was low in TIL cultures before coculture (3.4 ± 2.4%) or TIL cultures co-incubated with HLA-mismatched melanoma lines (data not shown) and significantly increased after coculture with autologous melanoma lines (30.1 ± 25.9%; p = 0.011) (Table 1), supporting the understanding that CD137 serves as a marker for tumor recognition. The gene discussed is TNFRSF9; the disease is melanoma.