MMP9 and rheumatoid arthritis: In contrast, the expression of MMP-9 (1.33-fold increase in OA, 2.86-fold in RA), ADAMTS-4 (1.65-fold increase in OA, 2.96-fold in RA), and ADAMTS-5 (1.07-fold increase in OA, 1.14-fold in RA) was increased in RA but did not show a significant change in OA (Figure 2B-C and Supplementary Figure S2).