Seminal studies have shed light on T-cell exhaustion in human cancers, where CD8 T cells lose proliferative capacity, the ability to produce tumor necrosis factor (TNFα), interleukin-2, and interferon-γ (IFNγ), and upregulation of inhibitory checkpoint receptors, such as PD-1 and CTLA-49–11. The gene discussed is IL2; the disease is cancer.