The RA synovium/SCID mouse model was also used to investigate the mechanisms of action of anti-rheumatic drugs in vivo and to test novel biologic agents for the treatment of RA, such as monoclonal antibodies directed against human IL-6R, CD147 or Fas, as well as T and B cell–related therapies using CTLA-4Ig, anti-CD20, and anti–IL-17 antibodies (266, 272–275). The gene discussed is BSG; the disease is rheumatoid arthritis.