Nakano et al. (2013a) have shown that DNA hypomethylation increases expression of numerous genes: growth factors/ receptors, extracellular matrix proteins, adhesion molecules, and matrix degrading enzymes, etc. Expression of the DNA methyltransferase-1 (DNMT1) is reduced on protein level in RASFs comparing to the osteoarthritis synovial fibroblasts (OASF), particularly when stimulated with cytokines or growth factors. Here, DNMT1 is linked to osteoarthritis.