The most used cancer serum biomarker is the CA125 immunoassay for ovarian cancer that detects the mucin MUC16. However, the monoclonal antibodies (OC125 and M11) used in the serum assay have epitopes that remain elusive. In this study, we demonstrate for the first time that neither N- nor O-glycosylation appear to substantially influence binding of OC125 and M11 mAbs and narrowed down the epitopes to a segment containing parts of two consecutive SEA domains with a linker.
