CD4 and neoplasm: Cross-presentation of tumor Ag by cDC1 must occur simultaneously to their immunogenic maturation such that they can deliver all of the signals required for the efficient priming of naïve CTLs or the reactivation of exhausted CTLs, including proper co-stimulation, activating cytokines, chemokines and CD4+ T cell help, in the tumor bed or upon migration to the draining lymph node.