Cyclin D1: Proteins and Enzymes

During the G1 phase of the cell cycle, a cell must choose between rest and cell division. A small subfamily of cyclin family molecules, termed cyclin D proteins (D1, D2, D3), promotes commitment to mitosis. They accomplish this by interacting with cyclin-dependent kinases (cdk4 and cdk6) to generate Ser/Thr kinase complexes that remove blocks on DNA synthesis.