MAPK8 and rheumatoid arthritis: Zhu et al. showed that the CYR61 is involved in RA development by enhancing the production of proIL-1β, which may exhibits powerful proinflammatory activity in the RA development [24]; Zhai et al. demonstrated that CYR61 induce the production of MMP-3 production in RA FLS through the P38, JNK-dependent AP-1 signaling pathway [41].