Interleukin 12 (IL-12) has been studied as one of the most potent cytokines for anti-cancer immunotherapy because it stimulates interferon (IFN)-γ production by T and natural killer (NK) cells, decreases the angiogenesis, and changes the cancer microenvironment from one that contains TH0 and M2-type phenotype macrophages to one richer in TH1 cells and inflammatory M1-type macrophages [7, 8]. The gene discussed is IFNG; the disease is cancer.