CDK5R1 and Alzheimer disease: In a pathological process such as AD, the activation of the calcium-dependent proteases m-calpain or μ-calpain can produce cleavage of the p35 and p39 activators, generating the p25 and p29 proteins, which are CDK5 activators with increased stability that induce a prolonged activation of CDK5 (Kerokoski et al., 2004; Peterson et al., 2010).