Induced by stress conditions, Ca2+- and calpain-dependent overexpression of p25 protein and consequently prolonged overactivation of the CDK5/p25 complex produces hyperphosphorylation of Tau in the brain, observed in neurodegenerative diseases [96], during chronic stress [97], after perinatal exposure to Pb [98], and also after embryological exposure to VPA in hippocampal and cortical neurons [57]. This evidence concerns the gene CDK5 and neurodegenerative disease.