{"type":"root","children":[{"type":"paragraph","children":[{"type":"text","value":"CA15-3 is also known as MUC1, a large transmembrane mucin-like glycoprotein present on the apical border of secretory mammary epithelial cells. Physiologically, MUC1 appears to play a role in cell adhesion and the high levels present in cancer may be causally involved in metastasis. CA15-3 has been detected with immunohistochemistry in a wide spectrum of carcinomas according to literature, including breast carcinomas (ductal and lobular), sarcomas (synovial sarcoma and malignant fibrous histiocytomas), and lung carcinomas."}]}]}