Cyclin-dependent kinase (CDK5) is a proline-directed serine/threonine kinase with activity primarily located in the central nervous system . Aberrant CDK5 activity is implicated in neurodegenerative disorders like Alzheimer's disease, Parkinson's disease, and other tauopathies . We used the crystal structure of holo CDK5 (PDB ID 4AU8, ) to define the binding site (Figure ).