CCND1 and Alzheimer disease: The transcriptomic analysis revealed that in AD mice the cell cycle regulatory gene, Cdc28 protein kinase regulatory subunit 2 (Cks2), was decreased while some cell cycle and apoptotic cell death-related factors, including cyclin D1, proliferating cell nuclear antigen, and cleaved caspase-3, were increased in the hippocampus of Tg-PS2m.