Figure 3. Effects of glucosamine (GlcN) on human retinal pigment epithelial cell line (ARPE-19) cell viability shown by calcein/PI flow cytometric analysis. A: ARPE-19 cells were treated for 5 days with 2.5 mM or 5.0 mM GlcN under serum-free conditions, and apoptotic cells were measured as the percentage of annexin V-positive/PI-positive cells. B: The quantitative data collected from the fluorescent images are expressed as the mean percentage±SD from three individual experiments.