MPPE1 and cancer: Conventional DC activating CD4+ T cells is a controversial topic where recent studies have implicated cDC1 as being capable of activating CD4+ T cell responses in cancer (2, 61, 64, 71, 72); however, previously it has been understood that cDC1 secrete lower levels of IL-12 in comparison to cDC2, and cDC2 are recognized as the predominant activators of CD4+ T cell anti-tumor immunity (23, 64, 67, 72).