New 'bouncer' molecule halts rheumatoid arthritis

Northwestern researchers have discovered why immune cells of people with rheumatoid arthritis become hyperactive and attack the joints and bones. The cells have lost their bouncer, the burly protein that keeps them in line the way a bouncer in a nightclub controls rowdy patrons. The protein, called P21, prevents immune cells from their destructive rampage. When the scientists injected a mimic of P21 into an animal model of arthritis, the disease process was halted.