A study showed that tumor-infiltrating CD8+ cytotoxic T-cells in AML had upregulated inhibitory receptors such as programmed cell death 1 (PD-1), cytotoxic T-lymphocyte antigen 4 (CTLA-4), T-cell immunoglobulin and mucin domain-containing protein 3 (TIM-3), and lymphocyte-activation gene 3 (LAG3) (Ozkazanc et al., 2016). The gene discussed is PDCD1; the disease is acute myeloid leukemia.