Cyclins are proteins that control the progression of cells through the cell cycle by activating CDKs. Different cyclins are present at different stages of the cell cycle, ensuring that each phase progresses in a controlled manner. CDKs are enzymes that, when activated by cyclins, phosphorylate target proteins to drive the cell cycle forward. CDK inhibitors are proteins that can bind to cyclins or CDKs to halt cell cycle progression, typically in response to DNA damage or other cellular stress.
