Aneuploidy – the result of the uneven separation of two matching sets of chromosomes during cell division – is found in more than 70 per cent of cancers and is now widely accepted as a major predisposing condition to cancer initiation and progression. Benjamen Montpetit is studying the role of the kinetochore, a protein complex that is of fundamental importance to the equal separation of chromosomes during cell division. Using yeast cells as a model, his research into the components responsible for chromosome transmission will result in a better understanding of the events involved in creating aneuploid cells and will provide a mechanistic basis for understanding chromsome instability in human cancers.