TNF and rheumatoid arthritis: Alternatively, the proteolytic shedding of membrane-bound TNF-α receptors ectodomains by the metalloprotease TNF-α converting enzyme (TACE, also known as ADAM17) [24,55], resulting in the release of soluble TNF-α binding proteins and reduction in cellular responses to TNF-α [56], may also play a part on the decreased levels of TNF-α receptors on T lymphocyte subpopulations in RA patients.