In eukaryotes, cell division is controlled by cyclin-dependent kinases
(CDKs). Here we summarize a few new developments on the regulation of
the cell cycle by CDK-cyclin complexes. We have focused on three aspe
cts in which there has been recent progress: the structural analysis o
f these complexes, the phenotypes of mice carrying knockouts of CDK in
hibitors and the role of proteolysis in the regulation of the cell cyc
le.