FAS and viral infectious disease: Cleavage of death domain receptors (such as FAS) or inactivation of their ligands could interfere with these specific apoptotic pathways, but are unlikely mechanisms in MMP28 mediated cell survival since the challenges used to induce apoptosis (serum deprivation, staurosporine and viral infection) do not share these pathways; however, roles of MMP28 in shedding of growth factors remains unknown.