CDK5 and Alzheimer disease: Moreover, inhibition studies of 24 against five different GSK-3β related kinases, including CDK-1, PKA, CDK-5, MAPK, and GSK-3α confirmed the compound specificity in inhibiting GSK-3β and CDK-5, suggesting manzamine framework as a promising scaffold for developing more potent and selective GSK-3β/CDK5 as anti-AD agents.