MMP9 and rheumatoid arthritis: The pro-angiogenic factors CD147, VEGF and TIMP-1, as well as MMP-9 activity, but not its expression, and proteasome 20S activity were elevated in the serum samples of RA patients relative to the controls (Figures 9A–H) or when those serum samples were added to the HT1080 fibroblast cell line (Figures 9K–P), whereas the levels of Tsp-1 were unchanged from those in controls.