ARG1 and neoplasm: They are also called myeloid-derived suppressor cells (MDSC) because that it has consistently been shown that these cells have a remarkable ability to suppress T-cell response through producing Arginase 1 (ARG1), inducible nitric oxide synthase (iNOS) and Transforming growth factor beta 1 (TGF-β1) in tumor-bearing mice [11], [12], [13].