MDSC recruitment can be induced by tumor-derived chemokines and cytokines, such as granulocyte-macrophage colony-stimulating factor (GM-CSF) [4–6], G-CSF, interleukin (IL)-6 [7], IL-1β, arginase 1 (ARG1), interferon (IFN)-γ [8–10]. Here, ARG1 is linked to neoplasm.