CD4 and neoplasm: Although CD4+ tumor-infiltrating T cells were significantly lower in IFNAR1-KO tumor-bearing mice as compared to WT tumor-bearing mice (Fig. 3C & D), IFNAR1-deficient CD4+ naïve T cells responded to antigen stimulation to generate antigen-specific CD4+ T cells as efficiently as WT CD4+ T cells in the mixed chimera mice (Fig. 4B).