ERBB2 and breast carcinoma: Many studies have been published on the concordance of HER2 immunohistochemistry and in situ hybridization in breast cancer,25 focusing usually upon the rabbit polyclonal antibody A408 (used in HercepTestTM) or the mouse monoclonal CB11 (used in the previous generation of Ventana Pathway®; Ventana), both FDA-approved kits.