Illustration of the US physician William G. Kaelin Jr. (born 1957). Kaelin's research has focused on tumour suppressor proteins, which prevent the proliferation of cancerous cells. Mutations in the genes for these proteins lead to loss of function and cancer. While studying the tumour suppressor responsible for the inherited cancer Von Hippel?“Lindau (VHL) disease, he found that the VHL protein interacted with hypoxia-inducible factor (HIF). HIF is responsible for sensing and responding to a lack of oxygen (hypoxia) in the cellular environment and disruption of the proper regulation of HIF enables tumours to proliferate despite a lack of oxygen. His work has laid the foundation for new anticancer therapies. Kaelin was awarded a share of the 2019 Nobel Prize in Physiology or Medicine along with Gregg L. Semenza and Peter Ratcliffe for his work on how cells adapt to oxygen availability.