CD4 and neoplasm: CD4+ and CD8+ T cells have been shown to mediate tumor rejection in an IFNγ-dependent fashion through different mechanisms, including up-regulation of molecules critical for antigen processing and presentation [59], differentiation of fully competent effector cells [60], secretion of angiostatic chemokines by stromal cells present within a tumor [61], and regulation of T-cell migration to the tumor site [62].