In the tumor microenvironment, T reg cells are a subset of CD4+ T cells and they can curtail the function of multiple immune cells by decreasing the production of interleukin (IL)-2 and interferon (IFN)-γ, increasing Th2 cytokine skewing, and directly inhibiting of endogenous generation and expansion (Humphries et al., 2010). The gene discussed is CD4; the disease is neoplasm.