ERBB4 and breast carcinoma: Processing of the full-length JM-a/CYT-1 or JM-a/CYT-2 isoforms by tumour necrosis factor-α-converting enzyme (TACE) and γ-secretase is known to generate an 80 kDa (p80) ERBB4 soluble intracellular fragment that undergoes nuclear translocation (Lee et al, 2002; Rio et al, 2000); p80 expression is associated with poor survival in breast cancer models (Junttila et al, 2005).