TNF and rheumatoid arthritis: The kinases p38α and p38β are typically activated by signaling from Toll-like receptors, as well as in response to oxidative stress, inflammatory cytokines, etc. The role of MAPK in transmitting signals from inflammatory cytokines such as TNF-α, which have proven to be successful targets in the treatment of RA, have made the MAPKs themselves attractive targets for the development of new therapies.