In tumor immunity, some CD4+ T cells enhance the anti‐tumor activity of cytotoxic T cells (CTLs) by promoting their infiltration of tumor sites, maintaining their activities, and performing antigen presentation.[90, 91] The activation of CD4+ T cells that recognize MHC‐II molecules is also crucial for anti‐tumor immunity.[92, 93] However, Treg cells suppress effector T cells in tumor immunity. This evidence concerns the gene CD4 and neoplasm.