EMT is frequently accompanied by loss of the epithelial marker E-cadherin, concurrent with elevated expression of vimentin [41–45], an intermediate filament that participates in cell motility [46], as well as increased expression of matrix metalloproteases-2 and -9 (MMP-2, MMP-9) [27–32] that are often assessed in the determination of poor prognosis in breast cancer patients [33–36]. This evidence concerns the gene MMP9 and breast cancer.