CD4 and neoplasm: Interestingly, we also found that cGAMP increased IFN-γ production from tumor-infiltrating CD4 T cells (figure 1C, D) as well as from MC38-OVA tumor-infiltrating OVA-specific CD4 T cells (online supplemental figure S2D), suggesting that STING activation enhances CD4 T-cell effector functions in vivo.