Figure 7.40

   Cyclin degradation during the cell cycle

The progression of eukaryotic cells through the division cycle is controlled in part by the synthesis and degradation of cyclin B, which is a regulatory subunit of the Cdc2 protein kinase. Synthesis of cyclin B during interphase leads to the formation of an active cyclin B–Cdc2 complex, which induces entry into mitosis. Rapid degradation of cyclin B then leads to inactivation of the Cdc2 kinase, allowing the cell to exit mitosis and return to interphase of the next cell cycle.