MMP9 and neoplasm: The tumour necrosis factor alpha TGF-α is a pro-inflammatory cytokine liberated by macrophages, T lypmhocytes, and mastocytes that induce the overexpression of some MMPs such as MMP-2, MMP-3, MMP-7, and MMP-9 in the tumour microenvironment, which increases the invasive capacity of the malignant cells [149].