For research use only. The M65® ELISA measures soluble keratin 18 (K18) (cytokeratin 18 [CK18]) released from dying cells and can be used to assess overall cell death (due to apoptosis and necrosis) of epithelial cells. The M65® ELISA is primarily intended to be used together with the M30 Apoptosense® assay, which specifically measures apoptosis.