In this AD setting, Aβ activates astrocytes, inducing an increase in intracellular Ca2+ that stimulates NADPH oxidase (NOX), causing neuronal death through oxidative stress; inducible nitric oxide synthase (iNOS) is also upregulated in these activated astrocytes (Abramov and Duchen 2005). Here, NOS2 is linked to Alzheimer disease.