Effect of nitrosative and oxidative stresses on BACE1 protein levels. To examine differential effects of nitrosative and oxidative stresses on BACE1 protein levels, various concentrations of SNOC (0, 0.001, 0.01, 0.1, 1, 10, 50, 100, 200, and 300 μM) (A and B), Ionomycin (0, 0.1, 0.3, 1, 3, 10 μM) (C) and H2O2 (0, 3, 10, 30, 100, 300 μM) (D) were added to primary rat cortical neurons for 1 hr. Then, BACE1 protein level was measured by probing BACE1 with a specific monoclonal antibody (5D3). While lower concentrations of SNOC downregulated the BACE1 protein level, high concentrations of SNOC showed no effect on BACE1 protein levels (A and B). BACE1 expression level was not affected by endogenous NO induced by ionomycin (C). However, lower concentration of H2O2 significantly upregulated BACE1 protein levels (D).