CDK5 and Alzheimer disease: Among the various kinases involved in AD, and particularly in Tau phosphorylation, glycogen synthase kinase-3β (GSK-3β) and cyclin-dependent kinase 5 (CDK-5) are the most implicated (Baumann et al., 1993; Flaherty et al., 2000; Sperber et al., 1995).