This site is part of a frame. If you arrived to this page directly, click here! TNF receptor shedding - model to explain TRAPS TNF-R1 (p55) mutations in TRAPS patients may impair cleavage of TNF-R1 by cell surface metalloproteinases. This impairs TNF-R1 shedding and, hence, the formation of soluble TNF-R1 (sTNF-R1). This leads to low TNF-binding capacity in body fluids and high levels of cell-associated TNF-R1, both resulting in increased TNF-signalling to the cells. The trimeric organization of TNF-R1 is not shown for simplicity.