Description: The NOK-1 monoclonal antibody reacts with human Fas (CD95) Ligand, a 40 kDa type II transmembrane glycoprotein. FasL is a member of the TNF family and is expressed by neutrophils, monocytes, and activated T cells and NK cells. The interaction of FasL with its receptor (CD95, Fas) induces Fas-mediated killing of lymphocytes. Human FasL is cleaved from the surface by matrix metalloproteinases (MMPs), resulting in a 26 kDa soluble form. Therefore for optimal detection of surface FasL on activated peripheral blood cells, incubation of cells with an MMP inhibitor is recommended.