DACAPO, A CYCLIN-DEPENDENT KINASE INHIBITOR, STOPS CELL-PROLIFERATIONDURING DROSOPHILA DEVELOPMENT

Most cell types in multicellular eukaryotes exit from the mitotic cell cycle before terminal differentiation. We show that the dacapo gene i s required to arrest the epidermal cell proliferation at the correct d evelopmental stage during Drosophila embryogenesis. dacapo encodes an inhibitor of cyclin E/cdk2 complexes with similarity to the vertebrate Cip/Kip inhibitors. dacapo is transiently expressed beginning late in the G2 phase preceding the terminal division (mitosis 16). Mutants un able to express the inhibitor fail to arrest cell proliferation after mitosis 16 and progress through an extra division cycle. Conversely, p remature dacapo expression in transgenic embryos results in a precocio us G1 arrest.