ERBB2 and breast cancer: Our IHC study of TweakR expression in breast cancer patient tumor samples covered the four major sub-types of breast carcinomas, i.e. ERBB2 positive, basal-like, luminal A, and luminal B tumors, and concluded that TweakR expression was correlated with ER/ERBB2 coexpression but not with ER or ERBB2 alone.