MMP9 and sarcoma: TAMs participate in tumor migration and invasion, and lead to an immunosuppression mechanism in many subtypes of sarcomas, through the expression of several markers (PD-1, PD-L1, CD80, SIRPA, CD206, CD209, CD146, CD14, CD68, CD163, CSF1R, etc.)and the secretion of multiple cytokines (IL-10, IL-6, IL-8, CSF1, IL-34, TGF-β, VEGF, etc.), chemokines (CCl2, CCL5, CCL18, CCL22, etc.)and other factors (such as MMP-9, COX2, and IDO1 etc.).