•Promotes CD4+ and CD8+ activity•Prolongs T cell survival•Secrete cytokine (IFNγ) and IgG•Recruit NK cells to eradicate cancer cells•Enhance antibody-dependent cell-mediated cytotoxicity (ADCC) by NK cells and phagocytosis in macrophages•Act as antigen presenting cells to stimulate anti-tumor response. This evidence concerns the gene CD4 and cancer.