ARG1 and neoplasm: Through further functional analysis, they confirmed that these cells were MDSCs, and by performing both in vivo and in vitro experiments, they showed that these cells can uptake and process tumor-associated antigens and promote the expansion of a preexisting Treg pool exclusively via arginase-1, which, in turn, induced antigen specific T-cell anergy and was responsible for the immunosuppressive state associated with an increasing tumor burden in lymphoma-bearing mice [85].