Without Emi1, nuclei (blue) balloon as they fill with extra DNA.

Talk about a career change. Di Fiore and Pines report on page 425 that a protein long thought to inhibit mitotic progression actually promotes mitosis and prevents cells from making too many copies of their DNA.

The cell cycle is driven by destruction. To advance to the next stage, a cell demolishes the road blocks that keep progress in check. Flagging these obstacles for destruction is the job of the anaphase promoting complex/cyclosome (APC/C). Its targets include cyclin B1 and securin, which block mitotic progression and anaphase. It was thought that APC/C itself was kept in check by a protein called Emi1. Emi1's breakdown early in mitosis allowed APC/C activation, the argument went.

Emi1's disappearance, however, begins too soon, Di Fiore and Pines now find. By tracking fluorescent Emi1, the authors found that it...

The Rockefeller University Press
2007
The Rockefeller University Press
2007
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