IL4 and neoplasm: Among tumor microenvironmental cell types, tumor-associated macrophages (TAMs) play a central role in supporting melanoma cell survival [11, 12], being recruited to the hypoxic tumor areas and “educated” by tumor cells [13–15] via paracrine signals (interleukin (IL)-4, IL-13, macrophage-colony stimulating factor (M-CSF), eotaxin, and transforming growth factor- β (TGF-β)) [16, 17] that convert these initial “antitumor fighters” (M1 macrophages) to “protumor slaves” TAMs (with M2 phenotypes).