Regarding possible targeted kinases, cyclindependent kinase 5 (CDK5) and GSK-3 are the most relevant accordingto in vitro studies evaluating tau phosphorylation.60,49 Kinase inhibitors are employed in many clinical fields, particularlyin cancer treatments.61 However, selectivityis the main problem related to the development of a kinase inhibitor,since the vast majority of these molecules bind to their target ATP-bindingsite.62 All of the approximately 518 kinasesof the human kinome use ATP as substrate to transfer the phosphategroup to different amino acids, mainly Ser, Thr, and Tyr. This evidence concerns the gene CDK5 and cancer.