GranzymeB (GranzymeB) is a serine protease most commonly found in the granules of cytotoxic lymphocytes (CTLs) and natural killer cells (NK cells). GranzymeB secreted by these cells acts together with perforin to mediate apoptosis in target cells. Recently, it has been discovered that many non-cytotoxic cells, from basophils to mast cells to smooth muscle cells, also produce GranzymeB. GranzymeB is involved in the induction of inflammation by stimulating the release of cytokines, as well as in extracellular matrix remodeling. Elevated levels of GranzymeB have been associated with a number of autoimmune diseases, some skin conditions and type 1 diabetes.