MMP9 and breast cancer: Matrix metalloproteinase-9 (MMP-9), also known as gelatinase B, is a 92-kDa zinc-dependent endopeptidase that promotes degradation of type IV collagen, the main component of basement membrane[4].Interestingly, although MMP-9 is highly expressed in breast cancer, its expression is rarely associated with malignant factors[5], [6].Furthermore, conflicting studies using experimental tumor systems reported correlations or lack thereof of increased MMP-9 expression with metastasis[7].