During apoptosis activated caspases-3, -6, -7 and -9 are able to cleave CK18 at specific peptide recognition sites. Caspase cleavage generates a neo-epitope which can be detected using the M30 and M65 assays, thus informing on the levels of apoptosis. In addition, the M65 antibody is also able to detect full length (intact) CK18, and thus provide information on the levels of necrotic cell death. The M65 ELISA uses the M6 antibody as the catcher antibody and M5 as the detection antibody. The M30 ELISA uses M5 as the capture antibody and M30 as the detection antibody.