TKT and Alzheimer disease: To evaluate whether Fyn TK is responsible for the increase in pAPP-Tyr in neurons from AD patients, we inhibited Fyn expression levels using Fyn siRNA (see Methods) in neurons from three AD patients (patient no. 31F, 38F, and 53M) in which we previously reported a progressive increase of Aβ42 levels in media and neuronal death after 4 weeks in culture [33].