CDK5 and Alzheimer disease: GsRb1 reduces calpain and p25 expression levels and attenuates β-amyloid peptide (25–35)-induced tau hyperphosphorylation in cortical neurons via the cyclin-dependent kinase 5 (CDK5) pathway, which promotes increased microtubule stability, intracellular calcium homeostasis in neuronal cells, neuronal cell protection and has significant potential to treat AD (Humbert et al., 2000; Chen et al., 2008; Shalaby et al., 2023; Sharari et al., 2023).