We are fascinated by the molecular mechanisms that govern progression through the cell division cycle. We use a variety of biochemical and genetic approaches, primarily in budding yeast, to study the cell biology and enzymology of two regulatory enzymes: the cyclin-dependent protein kinases and the ubiquitin ligase APC. These enzymes are particularly important in the control of mitosis, the complex process by which duplicated chromosomes are distributed to daughter cells at the end of the cell cycle.