Interestingly, expression analysis of MDA-byb1 and -hyb2 tumor hybrids revealed appropriate upregulation of EMT-associated genes, such as SLUG, collagen, fibronectin, N-cadherin, MMP3, and MMP9 [179], possibly indicating that tumor hybrids might have acquired a mixed E/M state. This evidence concerns the gene MMP9 and neoplasm.