In experimental hyperhomocysteinemia-induced renal damage, DNA hypermethylation and upregulation of dnmt1 and dnmt3a were followed by gene expression changes in crucial proteins involved in ECM regulation, including matrix metalloproteinase-9 (MMP-9) (an enzyme that participates in collagen degradation) and downregulation of MMP inhibitors, including tissue inhibitor of metalloproteinase- (TIMP-) 1 and -2. This evidence concerns the gene MMP9 and hyperhomocysteinemia.