MMP9 and neoplasm: In the context of tumors, epithelial tumor cells turn into mesenchymal cells through diminishing cellular conjunctions, decreasing focal adhesion, down-regulating epithelial markers such as E-cadherin and Keratin, up-regulating mesenchymal markers such as N-cadherin and vimentin, increasing cell mobility, remodeling cytoskeleton, and degrading extracellular matrix under the assistance of MMP-9 and other MMPs [144].