ERBB2 and cancer: Abundant tumor-derived exosomes are present in the plasma, ascites and pleural effusions of cancer patients, and they resemble miniatures of the host tumor cells by containing a host of tumor-associated antigens such as HER-2/neu, EGFR2, CEA, MART-1, gp100, TRP-1, mesothelin, and members of the HSP family including HSP 70 and HSP 90 [47,48,49,50].