Figure 8. Effects of glucosamine (GlcN) on transactivation of epidermal growth factor receptor (EGFR). Human retinal pigment epithelial cell line (ARPE-19) cells were treated with 2.5 mM or 5.0 mM GlcN, or 30 mM glucose for 24 h, stimulated with 10 ng/ml EGF, and stained with PE-conjugated anti-total-EGFR antibody and Alexa-Fluor-647-conjugated anti-p-EGFR antibody (Y845). The levels of phosphorylated (A) and total EGFR (B) were analyzed by flow cytometry. The data are representative of at least three independent experiments. Cells cultured under serum-free conditions were used as the control. C: western blot analysis of ARPE-19 cells cultured to 80% confluence; treated with 2 μg/ml tunicamycin, 30 mM glucose, or 5 mM GlcN in serum-free medium for a further 24 h; then stimulated with EGF for 5 min.