Cancer antigen 125 (CA125) for ovarian cancer as well as cancer antigen 15–3 (CA15-3) and cancer antigen 27–29 (CA27-29) for breast cancer are based on mucin proteins mucin-16 (MUC16) and mucin-1 (MUC1), respectively [139]. The gene discussed is MUC1; the disease is ovarian carcinoma.