Recent studies have demonstrated that the mRNA[16] and protein[6] of NOD2 were expressed in synovial tissue samples from RA patients, and NOD2 activation in synovial fibroblasts leads to the expression of proinflammatory cytokines and matrix-degrading enzymes via p38 mitogen-activated protein kinases (MAPK) and NF-κB signaling pathways [6]. Here, MAPK14 is linked to rheumatoid arthritis.