Regulation of Mus81–Eme1 Holliday junction resolvase in response to DNA damage

Structure-specific endonucleases are essential to resolve DNA-replication and repair intermediates, but their uncontrolled activity would compromise genomic stability. New data show that the Holliday junction resolvase Mus81–Eme1 is activated in response to DNA damage by sequential phosphorylation by cell cycle– and DNA damage–dependent Cdc2 CDK1 and Chk1 kinases, revealing how dual control restricts endonuclease activity in mitosis.