ERBB4 and breast carcinoma: Thus, we analysed the proteins of the HER-family (EGFR, p-EGFR, HER2, p-HER2, HER3, p-HER3, HER4) together with other proteins that are known to play important roles in general tumour progression (Akt, p-Akt, Erk, pErk), especially in breast cancer (uPA, PAI-1).