ERBB2 and cancer: Immunohistochemistry was applied for epidermal growth factor receptor (EGFR) as an established target in cancer diagnostics, insulin-like growth factor 1 receptor (IGF-1R) as an exploratory marker and phosphorylated human epidermal growth factor receptor 2 (phospho-HER2) as a signal transduction marker in order to test detectability of phosphorylated antigens.