MMP9 and neoplasm: Various stromal components, such as collagen, fibronectin, HA, VEGF, TGF-β, and CTGF are closely associated with a fibrotic and hypoxic tumour condition, which forms a hard mass and releases several proangiogenic factors, including VEGF, MMP-9, interleukin-8, and fibroblast growth factor-2 (129).