For cdks, one is enough

We can't turn sugars into a good pinot noir, but we do resemble yeast in one surprising way. Like the fungi, mammals require only one cyclin-dependent kinase (cdk) to complete the cell cycle, say David Santamaria, Mariano Barbacid (Spanish National Cancer Research Center, Madrid, Spain), and colleagues.

Although yeast need only one cdk to turn the cell cycle, the standard view was that mammals depend on at least five. Cdk2, Cdk3, Cdk4, and Cdk6 push the cell through interphase, whereas Cdk1 nudges it into mitosis. However, recent studies suggest otherwise. For example, lab mice are missing Cdk3 due to a mutation, and they show developmental—but not cell cycle—defects if they also lack any other pair of cdks.

To find out whether one cdk can suffice in mammals, the researchers analyzed mouse embryos that only manufactured...