Epithelial cells are arranged in tightly packed layers that line internal body cavities and provide a protective layer on the external surface of the body. Their purpose is to function as a barrier, protecting the body from mechanical damage, invading micro organisms and the loss of body fluids. Most epithelial CD antigens are cell adhesion molecules, which play a role in the tight junctions between epithelial cells to make them impermeable.
CD340/HER-2 ,a well-known epithelial tumor antigen, that is aberrantly expressed on the surface of tumor cells and provide autocrine growth signals. It is expressed in breast, ovarian, and several other types of epithelial tumors, but it has been primarily explored for its potential use in the immunotherapy of breast cancer.