Cell-cycle progression is precisely regulated during development by cell-cycle regulators that act at important developmental transitions. On p. 3669, Swan and colleagues now report that the Drosophila Cks gene, Cks30A,interacts with Cdk1 to regulate progression through female meiosis and the mitotic divisions of the early embryo. Cks is a highly conserved protein that nevertheless has distinct cell-cycle roles in different organisms. The researchers report that Cks30A corresponds to the Drosophilamaternal effect lethal gene remnants. Through phenotypic analysis of mutant alleles of Cdk30A, they show that Cks30A is crucial for Cdk1 activity in spindle assembly and anaphase progression during female meiosis and early embryonic mitosis. Finally, the authors provide novel mechanistic insights into how Cks30A controls these specialised cell cycles by showing that the Cks30A-Cdk1 complex regulates Cyclin A levels, possibly through the activity of the female germline-specific anaphase-promoting complex adaptor Cortex.