AXL and neoplasm: In order to preserve the macrophage capacity to activate anti-tumor immunity while preventing their differentiation into pro-tumor, immunosuppressive phenotypes, several groups including our own have examined the potential of targeting the pathways that lead to pro-tumor phenotypes in macrophages including IL-4 (4), arginase 1 (102), TGF-β (15), and Tyro3/Axl/Mer (TAM) tyrosine kinases (18, 101) in combination with RT.