INS and Alzheimer disease: Protein phosphatase 2 (PP2A) is the primary tau phosphatase implicated in AD and is suppressed by insulin administration in both human and animal studies (Gong et al., 1995; Kins et al., 2001; Vogelsberg-Ragaglia et al., 2001; Clodfelder-Miller et al., 2006; Papon et al., 2013).