Activated effector T cells can not only secrete cytokines such as interferon-gamma (IFN-γ) and tumor necrosis factor-alpha (TNF-α) to enhance immune responses and recruit other cytotoxic cells like dendritic cells (DCs) and natural killer cells (NKCs) to collaborate in antitumor activities, but they can also differentiate into memory T cells under strong tumor antigen stimulation, allowing for rapid response and control of tumor recurrence and metastasis upon re-exposure to tumor antigens [20–24]. The gene discussed is IFNG; the disease is neoplasm.