CDK5 and Alzheimer disease: Phosphorylation of tau occurs through the activity of tau kinases like protein kinase A (PKA), protein kinase C (PKC), mitogen‐activated protein kinases (MAPKs), proline‐directed protein kinases, such as extracellular signal‐regulated kinase (ERK), glycogen synthase kinase 3 beta (GSK‐3β), casein kinase 1 epsilon (CK1ε), and cyclin‐dependent kinase 5 (CDK5), which target S/T residues in S/T‐P sequences.[35, 36, 37] Many of the 16 S/T‐P sequences have been identified as irregular phosphorylation sites in AD.