Development of an organism from egg to adult requires sets of genes to be switched on and off at particular times and in the correct order. If genes are not switched off when necessary, cells can continue to multiply in an uncontrolled way leading to cancer. Gene regulation is also crucial in controlling the balance between renewal of stem cells and pathways to cell specialisation which are required to form the particular cells and tissues in the body. Since stem cells have a vast potential in regenerative medicine for the replacement of defective tissue, the understanding of gene control is crucial for harnessing the potential of these cells. Therefore studying the mechanisms whereby genes are switched off (as well as on) is vitally important for providing basic knowledge that has potential to lead to novel therapeutics.