PSEN1 and Alzheimer disease: We then searched for the tyrosine kinase (TK) that is involved in APP phosphorylation at Tyr682 in AD neurons and using mass spectrometry analysis we found that Fyn TK interacted only with this residue, and the interaction was elevated in brain tissue from AD modeling Gottingen minipigs [21] and patients both carrying PSEN1 gene mutations [20].