Moreover, K1 appears to be involved in endothelial cell immortalization [29] and its expression in epithelial and endothelial cells results in the production of vascular endothelial growth factor (VEGF) and matrix metalloproteinase MMP-9 [30], which can favor tumor angiogenesis and tumor cell growth in vivo [31,32]. This evidence concerns the gene MMP9 and neoplasm.