IBSP and rheumatoid arthritis: Intriguingly, 60.0% of RA patients were positive for anti-cit-OPN antibodies, while 0.0%, 16.7%, 50.0%, 30.0%, 3.3%, 10.0%, and 6.7% of RA patients had antibodies against citrullinated fibronectin, tenascin-C, α-enolase, BSP, type II collagen, vimentin, and fibrinogen, respectively (Fig. 1B).