Serum FSTL1 levels in 14 patients with active RA were significantly diminished following clinical improvement with treatment (infliximab alone in two patients, infliximab plus leflunomide in four patients, infliximab plus leflunomide plus methotrexate in two patients and leflunomide alone in six patients). The gene discussed is FSTL1; the disease is rheumatoid arthritis.