CXCR4 and carcinoma of esophagus: The aim of this study was to investigate the effects of single and combined inhibition of HER2 and CXCR4 receptor pathways, and to examine HER2- and CXCR4-expression levels under inhibition in order to determine a possible involvement of CXCR4-expression in HER2-positive esophageal carcinoma.