Also, an elevated level of ADAM17 expression was found in synovial tissue and mainly in macrophage- and fibroblast-like synovial cells and also cartilage in patients with RA, as compared with patients with osteoarthritis, and with normal cartilage (17-19) , suggesting that abnormal ADAM17 activity and expression may contribute to the development of several pathological conditions, including RA. This evidence concerns the gene ADAM17 and rheumatoid arthritis.