A protein involved in normal cell growth. It is found on some types of cancer cells, including breast and ovarian. Cancer cells removed from the body may be tested for the presence of human epidermal growth factor receptor 2 to help decide the best type of treatment. Human epidermal growth factor receptor 2 is a type of receptor tyrosine kinase. Also called c-erbB-2, HER2/neu, and human EGF receptor 2.