IL4 and neoplasm: Tumors secrete high levels of colony-stimulating factor 1 (CSF-1), which converts M1 macrophages (classically activated and tumoricidal) to M2 macrophages (alternately activated, tumor-promoting) along with Th2 cytokines (e.g., IL-4, IL-10, TGFβ1, and PGE2) and stimulates tumor growth and metastasis [121,122].