IL4 and neoplasm: Within the tumor microenvironment, acquisition of M2 phenotype is promoted in response to IL-10 and IL-4 cytokines, in addition to some growth factors such as vascular endothelial growth factor A (VEGF-A)158,159 and catecholamines (noradrenaline and adrenaline) released by tumor-associated sympathetic fibers and adrenal glands.160 As with other immunosuppressive cell populations, reducing M2 macrophages likely improves patient prognosis, as it has been recently shown in skin cancer patients.