MMP9 and rheumatoid arthritis: In a study, we demonstrated that the migration, invasion, and expression of MMP2, MMP9, and p-FAKin RA-FLSs were decreased by the intracellular calcium chelating agent BAPTA-AM or Rac1 specific blocker NSC23766 (19).Thus, we conclude that ASIC1a maybe a master regulator of synovial invasion via the Ca2+/Rac1 pathway and that inhibition of synovium invasion maybe one of the mechanisms forASIC1a in the treatment of RA.