Fig. 1: The expression level of Dsg2 might be involved in EGFR expression on the cell membrane.

a Representative photomicrographs of immunohistochemical staining for EGFR in human tissues from patients with GBC. Scale bars: 100 μm. b The correlation between the EGFR expression pattern and survival rates in patients with GBC. Kaplan–Meier-based survival analysis for patients with membranous vs. cytoplasmic EGFR expression. c The isolation of GBC cells according to cell-surface EGFR expression using a FACSAria sorter, d cetuximab resistance in tumor cells with low EGFR expression. Cells expressing high or low levels of EGFR on the cell membrane were pretreated with 40 μg/ml cetuximab for 1 h, after which they were stimulated with 50 ng/ml of EGF for 48 h. Cell viabilities were assessed by MTT assays. *p < 0.05 compared with EGFR-high cells. e The expression levels of cell-junction cadherin proteins within EGFR-high and EGFR-low cell lysates were analyzed by western blotting using indicated antibodies. f Representative immunostaining of EGFR and Dsg2 in tissues of patients with GBC. Scale bars: 50 μm. g Western blot analysis of cytosolic and membrane protein fractions in shCtrl and shDsg2 cells. EGFR was dominantly expressed in the cytosolic fraction of both SNU308 shDsg2 and JCRB1033 shDsg2 cells.