Figure 3: NRG-1 promotes GSH synthesis by stimulating EAAT3-mediated cysteine uptake. (a) EAAT3-mediated [35S]-cysteine uptake was increased by NRG-1 with an EC50 of 3.91 pM. Cells were treated with 1 nM NRG-1 for 1 hr, . Intracellular levels of cysteine (b) and GSH (c) and the ratio of GSH/GSSG (d) were increased by 1 hr NRG-1 (1 nM) treatment. These effects were blocked by pretreatment with the PI3 kinase inhibitor wortmannin (100 nM), . Data represent mean values ± SEM. Asterisks () indicate a significant difference () from control group. # indicates a significant difference () from NRG-1 treated group.