Several potential TLR2 ligands have been implicated, including Acute Serum Amyloid-A, Heat Shock protein/GP96, Fibronectin fragments, Hyalauronidase oligosaccharides and HMBG-1, all of which are highly expressed in RA synovial fluid [25]–[29]. The gene discussed is FN1; the disease is rheumatoid arthritis.