Timing is everything: regulation of mitotic exit and cytokinesis by the MEN and SIN

Proper completion of mitosis requires careful coordination of numerous cell ular events. It is crucial, for example, that cells do not initiate spindle disassembly and cytokinesis until chromosomes have been properly segregate d. Cells have developed numerous safeguards or checkpoints to delay exit fr om mitosis and initiation of the next cell cycle in response to defects in late mitosis. In this review, we discuss recent work on two homologous sign aling pathways in budding and fission yeast, termed the mitotic exit networ k (MEN) and septation initiation network (SIN), respectively, that are esse ntial for coordinating completion of mitosis and cytokinesis with other mit otic events.