FYN and Alzheimer disease: Overactivation of NMDARs causes excitotoxicity and neuronal cell damage, and chronic NMDAR hyperactivity contributes to neuronal loss in the development of AD [37, 55] We demonstrated that hyperpalmitoylated FYN increases NMDAR phosphorylation, resulting in ZDHHC21T209S/T209S neurons being more susceptible to NMDA-induced excitotoxicity of postsynaptic receptors, similar to that reported in Ppt1−/− neurons [25].