Focus issue: choreographing the dance of the mitotic kinases.

Phosphoproteomic analysis of mammalian or yeast cells arrested in mitosis provides a comprehensive view of how phosphorylation contributes to this process, and the research highlighted in this issue implicates previously unrecognized players in this complex process of cell division. Analysis of substrate selectivity and the motifs targeted by specific kinases suggests that cells combine negative and positive site selection, along with spatial segregation, to ensure that the multiple kinases that participate in mitosis find their proper targets. Because alterations in the activities of these kinases can lead to uncontrolled cell proliferation and because of their essential roles in regulating cell division, these kinases are the targets of anticancer therapeutic agents. The research highlighted in this issue not only provides rich data sets for future investigation but also has the potential to lead to the development of new treatments aimed at reining in uncontrolled cell proliferation.