The promise for the treatment of proliferative disorders, with incalculable potential benefits to human health, has driven basic research into the genetic control of cell division for decades. However, what determines when cells initiate their division remains mysterious. It is as if we are staring at a beautiful engine, with little knowledge about what turns it on. How cells are set off to a new round of cell division, remains as one of the most fundamental, unanswered questions. It is virtually unknown which cellular pathways affect initiation of division, which factors operate within each pathway, the extent of interactions between pathways, and how each pathway is molecularly linked to the machinery of cell division. Our studies aim to answer these questions using baker's yeast. This model organism has a machinery of cell division that is very similar to that of human cells, and it is suited for genetic and biochemical studies.