EGFR and gastric cancer: Gastric cancer cell line NCI-N87 expressed high level of HER2 and EGFR (Fig. 2a, c), and HER2 and EGFR cell surface level were very close (Fig. 2d), indicating that these EGFR and HER2 had great chance to exist on cell surface in the form of HER2/EGFR heterodimer upon ligand bindings.