MAPT and Alzheimer disease: In addition, CDK5 induces hyperphosphorylation of tau and enhances tau aggregation in p25 (CDK5 activator) and h‐P301L double‐Tg mice (Noble et al., 2003), and exposure of 3xTg mice (a model of AD with both Aβ and tau pathology) to LPS increases tau phosphorylation via CDK5 activation (Kitazawa et al., 2005).