For example, TGF-β, FGF2, EGF, and interleukin 6 (IL-6) stimulate cancer cell proliferation; VEGF and platelet-derived growth factor (PDGF) promote angiogenesis; MMP-2 and MMP-9 degrade extracellular stroma; and CCL22 recruits Tregs lymphocytes to cause tumour immunosuppression [26]. The gene discussed is MMP9; the disease is cancer.