The only study supporting the anti-RA function of SUMOylation reported that the expression of SUMO2 in RA tissue or RASFs is significantly higher than that of OA tissues and is increased in the synovium and synovial fibroblasts of human TNF-transgenic (hTNFtg) mice, a common RA model [134]. This evidence concerns the gene TNF and rheumatoid arthritis.