A previous investigation has demonstrated that the depletion of arginase I-producing MDSC in 4T1 mammary adenocarcinoma-bearing mice with antibody treatment reduces tumor size and metastasis to a certain extent but still not comparable with the group treated by anti-TGF-β antibody, in which a significant reduction of tumor size and metastasis was observed[9]. This evidence concerns the gene TGFB1 and neoplasm.