Figure 5. NAC treatment suppresses light-induced ER stress in photoreceptors and RPEs. The cells were treated with NAC (5 mM for 661W cells; 2.5 mM for ARPE-19 cells) or vehicle and cultured under light/dark conditions for 3 days, the levels of ER stress markers were determined with western blotting, and β-actin was referenced as an internal control. Three independent experiments are conducted two weeks apart. The results are presented as the mean± SEM. n (per group) =3, **P < 0.01.