CDK5, in complex with cleaved CDK5R1 (p25), which ensures nuclear localization (Patrick et al. 1999, Lee et al. 2008), phosphorylates TP53 (p53) on serine residues S15, S33 and S46. CDK5-mediated phosphorylation of TP53 promotes transcription of pro-apoptotic genes and neuronal cell death (Zhang et al. 2002, Lee et al. 2007, Lee et al. 2008).