Fig. 1

Effects of EGFR inhibitors on immortalized-human esophageal epithelial cells. EPC2-hTERT, an immortalized-human esophageal epithelial cell line, was treated with erlotinib (1 μM) or cetuximab (100 μg/mL). a Phosphorylated- and total-EGFR protein levels in EPC2-hTERT cells treated with or without erlotinib or cetuximab for 24 h, determined by western blotting. b Cell growth of EPC2-hTERT cells treated with or without erlotinib or cetuximab for 72 h, determined by cell count. Results are presented as means ± SD (bars). (** p < 0.01 vs. vehicle control; n = 3). c Cell cycle analysis of EPC2-hTERT cells treated with or without erlotinib or cetuximab, analyzed by EdU assay. Cells in S phase are plotted in p3, and cells in other phases in p2. The experiments were conducted in triplicate, and results are presented as means ± SD. Representative data are shown. (** p < 0.01 vs. vehicle control; n = 3). d Involucrin mRNA expression levels in EPC2-hTERT cells treated with or without erlotinib or cetuximab for 72 h. The mRNA levels for the IVL gene relative to the untreated cells were determined by QPCR. The gene for β-actin served as an internal control. (**p < 0.01 vs. vehicle control; n = 3). e Involucrin protein production levels in EPC2-hTERT cells treated with or without erlotinib or cetuximab for 72 h, determined by western blotting. f Phosphorylated- and total-EGFR protein levels in EPC2-hTERT cells treated with human recombinant EGF (rEGF) (20 ng/mL) for 48 h, determined by western blotting. g Involucrin mRNA expression levels in EPC2-hTERT cells treated with rEGF for 48 h, determined by QPCR. (**p < 0.01 vs. vehicle control; n = 3). h Involucrin protein production levels in EPC2-hTERT cells treated with rEGF for 48 h, determined by western blotting