MAPT and Alzheimer disease: The findings reported here bolster the view that cdk5 plays a critical role in AD; previous work showed its importance in mediating Aβ-induced synaptic dysfunction [59] and PSD protein degradation [13], [17] as well as in tau hyperphosphorylation, transcriptional derangement, amyloidogenesis and neuronal apoptosis [60]–[63].