CD4 and neoplasm: Drives differentiation of tolerogenic CD4+ Th2 cells in the tumor microenvironment (52); induces cancer-promoting phenotypes in tumor-associated macrophages (M2) and DCs (31, 53); IL-4 mediates survival and proliferation of cancer stem cells (54–56); IL-13Rα2 signaling promotes tumor invasion and metastasis (57–59)