CD4 and neoplasm: Adding the induced Treg by tumor explants with or without anti-PD-1 or/and anti-IL-21 treatment strongly inhibited the proliferation of responder T cells (both CD4 and CD8) (Supplementary Figures 4A, 5A), reduced the IFN-γ, IL-2 levels of CD4+ T cells (Supplementary Figures 4B, D), and cytotoxicity, GranzymeB, Perforin levels of CD8+ T cells (Supplementary Figures 5B, E).