MMP9 and neoplasm: Finally, other regulatory mechanisms of MMP-9 expression are mediated by MMP-9 allelic variation (rs3918251GG (A>G) and by the over-expression of SOX4 responsible for the concomitant up-regulation of MMP-2/9 and NF-κB/p65 and, consequently, for a more aggressive tumor phenotype [78,79].