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Letter

Nature Cell Biology 9, 565–572 (1 May 2007) | doi:10.1038/ncb1570

Flies without a spindle checkpoint

Eulalie Buffin , Doruk Emre & Roger E. Karess

Mad2 has a key role in the spindle-assembly checkpoint (SAC) — the mechanism delaying anaphase onset until all chromosomes correctly attach to the spindle. Here, we show that unlike every other reported case of SAC inactivation in metazoans, mad2-null Drosophila are viable and fertile, and their cells almost always divide correctly despite having no SAC and an accelerated 'clock', which is caused by premature degradation of cyclin B.