The observed stability in HER2 expression is also supported by older studies on breast cancer (e.g. Niehans et al, 1993) and also by studies on other tumours such as ovarian cancer (Tewari et al, 2000), cutaneous squamous carcinomas (Ahmed et al, 1997) and urinary bladder carcinomas (Wester et al, 2002). Here, ERBB2 is linked to breast cancer.