HAS3 was upregulated and correlated with EGFR in human ESCC. (A) Real-time PCR of HAS3 mRNA from biopsy specimens from normal mucosa (n = 13) and human ESCC differentiated into TNM staging (defining tumour size (T), lymph node involvement (N) and existence of metastases (M)) (n = 20), mean ± SEM, *, p < 0.05. (B, C) EGFR expression was determined in the same biopsy specimens as in (A) and correlated to HAS3 expression in normal mucosa (B) and in ESCC (C). HAS3 expression was significantly correlated to EGFR expression in ESCC. (D) EGF stimulated HAS3 mRNA expression in the human ESCC cell line OSC1. This effect was rescued by use of the EGFR tyrosine kinase inhibitor erlotinib and the molecular anti-EGFR antibody cetuximab. Data are mean ± SEM; n = 3-5; ***, p < 0.001.