Fig. 1

Representative images of H&E and ERBB2 immunohistochemical staining and FISH in the primary GEJ cancer tissue. Low (a: ×100) and high (b: ×400) magnification images of H&E stained section of the primary GEJ tumor. c Negative ERBB2 immunohistochemical staining in the primary GEJ tumor (×400). d Negative ERBB2 gene amplification by FISH. Tissue section showing ERBB2 gene copies (red) and chromosome enumeration probe 17 (CEP17) copies (green)