• RT induces TGF-ß and IL-4 leading to production of alternatively activated/M2 macrophages which inhibit anti-tumor immune responses • Macrophages promote matrix remodeling, vasculogenesis which support tumor regrowth post-RT • Inhibiting macrophages via CSF-1R, Axl, Cd11b results in better anti-tumor responses post-RT. This evidence concerns the gene IL4 and neoplasm.