ERBB3 and familial pancreatic carcinoma: High levels of pHER3 expression were confirmed in the AsPC-1 pancreatic cancer cell line by western blotting, anti-HER3 monoclonal antibody (3D4) and anti-HER2 monoclonal antibody (trastuzumab) significantly down-regulated the expression of pHER3, and two drug combination showed synergistic inhibitory effect (Fig. 1a).