CDK4 and Alzheimer disease: Markers of cell-cycle progression (Cdk4, cyclin D, phospho-Rb, E2F1, Cdk1, and cyclin B) were elevated in the CP-AD group compared to both the P-AD and N groups, regarding nuclear expression; some markers, such as Cdk4, phospho-Rb, and Cdk1, were found elevated in the CP-AD group compared to the N group for cytoplasmic expression.