A recent study by Gros et al. [46] demonstrated that expression of PD-1, TIM-3 or LAG-3 on CD8+ TILs identifies the tumour-reactive clonotypes, and that PD-1+, TIM-3+ and LAG-3+ CD8+ melanoma TILs expanded in IL-2 were capable of secreting IFNγ and lysing tumour in vitro. The gene discussed is CD8A; the disease is melanoma.