Although lower levels of MMP-9 are associated with a better prognosis of tumour treatment, higher levels do not necessarily mean the opposite effect, given the role of MMP-9 in the control of angiogenesis and its ability to cleave anti-angiogenic precursors and activate angiostatin and other anti-angiogenic factors such as endostatin and tumstatin, which consequently reduces tumour growth and blood vessel density [28]. The gene discussed is PLG; the disease is neoplasm.