The coordination of many mediators, including cytokines (interleukin (IL)-10, tumor growth factor (TGF)-β, and prostaglandin E2), membrane-bound ligands (B7-H1), and programmed cell death-1 (PD-1), is required to suppress tumor cells and immunosuppressive T-regulatory cells (Tregs) such as FOXP3+CD4+ cells. The gene discussed is PDCD1; the disease is neoplasm.