ACAN and rheumatoid arthritis: However, the effect of anti-TNF-α therapy on cartilage aggrecan metabolism in RA remains unknown, which is why the main objective of this study was to evaluate quantitatively the serum biochemical markers of aggrecan turnover—i.e., ADAMTS-4 and ADAMTS-5, the proteinases responsible for aggrecan catabolism and TIMP-3, the previously mentioned proteinase tissue inhibitor—in female RA patients treated with TNF-α antagonists.