N1-TANs enhance the tumor cytotoxicity and attenuate immune suppression by producing tumor necrosis factor α (TNF-α), intercellular adhesion molecule-1 (ICAM-1), reactive oxygen species (ROS) and apoptosis-related factor (Fas), and by reducing the expression of arginase, while N2-TANs participate in tumor migration and metastasis through the expressions of arginase, matrix metalloproteinase 9 (MMP-9), VEGF and chemokines [11]. This evidence concerns the gene MMP9 and neoplasm.