Playing polo in G1: a novel function of polo-like kinase-2 in centriole duplication.

Centrosomes contain a pair of centrioles that duplicate once during the cell cycle to give rise to two mitotic spindle poles, each containing one old and one new centriole. Centrosome duplication initiates at the G(1)/S transition in mammalian cells, and is completed during S and G(2) phase. The localization of a number of protein kinases to the centrosome has revealed the importance of protein phosphorylation in controlling the centrosome duplication cycle. Recent studies have shown that polo-like kinase-2 is required for centriole duplication in mammalian cells. In this article I discuss the implication of these findings to our current understanding of centrosome duplication.