GPX1 and Alzheimer disease: We explored this and found that Nrf2 levels in the livers of the AD mice were not depleted and instead had a tendency to increase, but the phosphorylation of Nrf2 was reduced and the expressions of the downstream antioxidant proteins CAT, NQO1, GPX1, and NQO1 were significantly reduced, indicating that the Nrf2 antioxidant systems in the livers of the AD mice were also in suppressed states.