ERBB2 and breast cancer: HER2 is a transmembrane receptor most often associated with breast cancer but is overexpressed in a host of other malignancies; MUC16 is a type I transmembrane mucin most often associated with ovarian and pancreatic cancer; and CD24 is a small, membrane-bound glycoprotein that is overexpressed in several solid carcinomas, such as esophageal squamous cell carcinoma and ovarian cancer (16).