Figure 6. Effects of GlcN on EGF-stimulated phosphorylation of ERK, AKT, and STAT3. Human retinal pigment epithelial cell line (ARPE-19) cells were pretreated with 2.5 mM or 5.0 mM glucosamine (GlcN) under serum-free conditions for 24 h and incubated for a further 30 min in the presence or absence of 10 ng/ml epidermal growth factor (EGF). The same blot was probed with anti-phospho antibody or anti-total antibodies for ERK, AKT, and STAT3.