MMP9 and rheumatoid arthritis: In that regard, the MMPs most often associated with chronic inflammation characteristic of RA and OA are MMP-1 (collagenase-1), MMP-2 (72kDa gelatinase), MMP-3 (stromelysin-1), MMP-10 (stromelysin-2), and MMP-9 (92kDa gelatinase) [6].