One focus in the mechanism of neuronal death in AD is the aberrant expression of cell-cycle-related proteins, such as cdc2, cdk4, cyclin B1, and cyclin D, which mediate cell cycle progression, in vulnerable neurons of the AD brain [11-14]; these molecules play essential roles in neuronal death associated with various paradigms of neuronal death [15]. The gene discussed is CCNB1; the disease is Alzheimer disease.