I am interested in regulation of the cell-cycle and the deregulation that leads to cellular proliferation and cancer. This interest has resulted in the demonstration that Polo kinase is essential for the metaphase to anaphase transition in Drosophila larval neuroblasts and that Polo may be involved in the spindle checkpoint (JCB 2001, 153: 663-675). In addition it was demonstrated that mutations in Drosophila Cdc27 enhanced the centrosomal phenotype of weak mutations in Polo kinase, causing them to resemble stronger Polo mutants (JCS 2003, 116: 4147-4158) suggesting that the Anaphase Promoting Complex, a target of the spindle checkpoint, is involved in the activation of Polo kinase to promote centrosome maturation. Recent work has moved from studying M-phase to the regulation of S-phase and the response to DNA damage. This work has demonstrated that TopBP1, a DNA replication and repair factor, is aberrantly expressed in breast cancer (Histopathology 2007, 50: 418-424) and contains several chromatin modification domains (Biochem J. 2006, 400:573-582). Current work is focusing on how TopBP1 regulates DNA replication, genome segregation, repair and transcription via interaction with other proteins.