How do roscovitine and tamoxifen's different mechanisms both effectively reduce Cdk5 levels in AD?

The abstract states these drugs have different mechanisms of action but both target Cdk5, yet provides no mechanistic explanation. Understanding these distinct pathways is crucial for optimizing combination therapy and predicting efficacy. Gap type: unexplained_observation Source paper: Potential cure of Alzheimer's disease by reducing the level of Cdk5 using two drugs, each with a different modus operandi. (2025, Journal of Alzheimer's disease reports, PMID:40290779)