Because oligomeric Aβ decreases PtdIns(4,5)P2 levels in AD (Berman et al., 2008), as we also observed, there is a possibility that SHIP2 activation together with either Synj1 upregulation or PTEN downregulation induces the imbalance in the phosphoinositide pool between PtdIns(3,4)P2 and PtdIns(4,5)P2, and leads to AD pathogenesis. Here, SYNJ1 is linked to Alzheimer disease.