Cdk activation by phosphorylation: linking growth signals to cell cycle control.

Cells adjust their proliferation in response to extrinsic factors and nutrients. Such inputs must reach the cell cycle machinery to ensure proper cell proliferation. This minireview focuses on evidence suggesting that phosphorylating the T-loop domain of cyclin-dependent kinases may be a critical and conserved conduit for these external signals. Understanding this regulatory mechanism could provide crucial insights into how all eukaryotic cells integrate external information to decide whether or not to divide.