The switch from a mitotic cell cycle to an endocycle (DNA replication without mitosis) that occurs in Drosophila oogenesis is an excellent system in which to study how developmental signals control the cell-cycle machinery. Sun and Deng now report that the downregulation of the homeodomain protein Cut by Notch contributes to the mitotic cycle/endocycle switch and to cell differentiation in Drosophila follicle cells (see p. 4299). Cut, they show, is expressed in proliferating follicle cells but not in endocycling cells. This downregulation of Cut expression is induced by Notch signaling. The researchers report that Cut promotes the expression of Cyclin A, the essential mitotic cyclin, by negatively regulating Fizzy-related, an anaphase-promoting complex/cyclosome adaptor. These and other results suggest that Cut functions as a linker between Notch and the genes that are involved in cell-cycle progression and cell differentiation.