CDK5 and Alzheimer disease: A surprising result from the microarray study was that the expressions of several key genes involved in the regulation of AD pathology include the genes encoding microtubule-associated protein (Tau), the components of the γ-secretase complex PS1, Gsk-3β, protein phosphatase 2 (Ppp2ca), Cdk5, Cdk5r1, Capn1, Csnk1α1, and Csnk1δ decreased.