ERBB4 and breast carcinoma: The prognostic significance of HER3 and HER4 expression in breast carcinoma differs in several reports (Kew et al, 2000; Suo et al, 2002; Bieche et al, 2003; Witton et al, 2003; Abd El-Rehim et al, 2004; Tovey et al, 2004).