ERBB2 and neoplasm: We evaluated the levels of ErbB2 (rat neu or human HER2) in MMTV-PyVT/HdhQ7/Q7 and MMTV-PyVT/HdhQ111/Q111 tumours by immunohistochemistry and found a marked increase of ErbB2 in polyQ-expressing tumours as compared to the control tumours (Fig 5A, left panels).