To assess the role of B1R in phosphorylation of Erk1/2, RA FLSs were preincubated with B1R inhibitor (SSR240612) for 1 hour before stimulation with sCD13 (4.8 nM) for 15–20 minutes, and Western blots were performed. Here, BDKRB1 is linked to rheumatoid arthritis.