How Cell Cycle Regulator Were Identified?

How Cell Cycle Regulator Were Identified? The central components of the cell-cycle control system are cyclin-dependent protein kinases (Cdks), whose activity depends on association with regulatory subunits called cyclins. Oscillations in the activities of various cyclin-Cdk complexes leads to the initiation of various cell-cycle events. How do you think cell controls and regulates this process?