In human arthritis, the BMP ligands 2 and 6 [59] and their receptors BMPR1a and BMPR2 [60] were upregulated, while BMP ligands 4 and 5 were downregulated in RA and osteoarthritis (OA) synovium in comparison to normal control samples. The gene discussed is BMPR2; the disease is rheumatoid arthritis.