Figure 5. Effects of glucosamine (GlcN) on the expression of cell-cycle regulators. Human retinal pigment epithelial cell line (ARPE-19) cells were deprived of serum for 24 h, stimulated with 10 ng/ml epidermal growth factor (EGF) with or without the addition of GlcN for the indicated times, lysed, and subjected to immunoblotting analysis with antibodies directed against the indicated proteins. The data are representative of at least three independent experiments.