FYN and Alzheimer disease: Interestingly, striatal-enriched protein tyrosine phosphatase (STEP), the main phosphatase of GluN2B and GluA2 subunits of NMDA and AMPA receptors, as well as of synapse-related kinases, Fyn, Pyk2, and ERK1/2, was reported to be increased in AD including in post-mortem AD patients and several AD mice models such as the Tg2576, J20, APP/PS1, and 3×TG mice [32,33,34].