CDK5 and Cognitive impairment: Utilizing this new inhibitor of Cdk5, we investigated the downstream effectors of Cdk5/p25 that may mediate neuronal demise and subsequent cognitive impairments associated with injury through Cdk5 phosphorylation site-directed phosphoproteomics of the hippocampus from control, rTBI, and rTBI rats treated with 25–106 (rTBI + 25–106) 48 h post-injury, which corresponded to the generation of the p25 fragment observed previously (Fig. 6A).