Additionally, Cdk5 phosphorylation of Drp1 occurs in mouse primary cortical neurons exposed to amyloid beta (Aβ1‐42).202 Neurons treated with Aβ1‐42 exhibited increased fission and apoptosis that could be ablated by impairing Cdk5, which may indicate that Cdk5 activation of Drp1 may be involved in AD pathophysiology.202 Intriguingly, these reports place a cell cycle enzyme in stress response pathways within postmitotic cells. The gene discussed is CDK5; the disease is Alzheimer disease.