showed that accumulation of Aβ in AD, due to failure of NGF signal, may induce TrkA phosphorylation and interaction with p75NTR and PS1, shifting the neurotrophic signal of TrkA to the apoptotic signal of p75NTR via the activation of phospholipase Cγ (PLCγ) and catalyzed by Src and CDK5 kinases (Matrone et al. 2009). This evidence concerns the gene PSEN1 and Alzheimer disease.