CDK4 and Alzheimer disease: This clustering displays an expression pattern composed of high levels of cell-cycle progression markers (Cyclin D, ppRb, Cdk4, Cdk1, E2F1, Cyclin B) and apoptosis markers, along with low levels of cell-cycle inhibitors and DNA repair markers (p27, Cdk5, ppAKT, p53, PTEN) in CP-AD individuals; P-AD and N individuals show the opposite pattern, with low levels of cell-cycle progression markers and apoptosis markers and high levels of cell-cycle inhibitors and DNA repair markers.