ARG1 and lung cancer: Studies of mouse models of melanoma and breast and lung cancer showed that C5aR-mediated pathways are linked to the differentiation of MDSCs and activation of these pathways is associated with the production of immunomodulators such as arginase-1 (Arg-1), IL-10, TGF-β1, cytotoxic T lymphocyte antigen 4 (CTLA4) and PDL-1 [17, 44, 45].