Figure 1. Viability of human retinal pigment epithelial cell line (ARPE-19) cells and determination of the LC₅₀ concentration in the presence of GlcN. ARPE-19 cells were cultured in Dulbecco’s modified Eagle’s medium and 10% fetal bovine serum (FBS). The medium was changed after 24 h, and glucosamine (GlcN) was added in concentrations between 0 mM and 140 mM. After 24 h, viability was determined with 2% trypan blue. The LC₅₀ was 39.0 mM. An LC₅₀ value is the concentration of a material that will kill 50% of the test cells.