ERBB2 and breast cancer: Exosomes from breast cancer cells (MCF-7) and normal mammalian epithelial cells (MCF-10A) were collected and Western blotting was used to detect EpCAM, PSMA, HER2, EGFR, CEA, and CA125, and a marked increase in expression of EGFR, CEA, and CA125 was observed in MCF-7.