MAPKAPK2 and rheumatoid arthritis: Mitogen-activated protein kinase–activated protein kinase-2 (MAPKAPK2 or MK2) is an intracellular serine/threonine kinase substrate downstream from p38 mitogen-activated protein kinase (MAPK) and its activation by p38 is implicated in many inflammatory diseases including postoperative ileus, pancreatitis, atherosclerosis, rheumatoid arthritis and cancer14, 15, 16, 17, 18, 19.