To investigate which ErbBs are involved in BTC-induced beta cell proliferation, we first checked the expression of ErbBs in MIN-6 insulinoma cells and mouse islets and observed that all known ErbB isoforms (ErbB-1, ErbB-2, ErbB-3, ErbB-4) were expressed both in MIN-6 cells and islets of C57BL/6 mice. The gene discussed is EGFR; the disease is pancreatic insulinoma.