MUC16 and cancer: CA-125 (cancer antigen-125) is a glycoprotein that is ubiquitous on the surface of the normal mesothelial cells lining the body cavities.20 High cell surface expression of CA-125 is reported in tumors such as ovarian cancer, mesothelioma and some other cancers.21 This molecule is also released into the circulation and its serum level is used for assessing disease progression in ovarian cancer.