The 2019 Nobel Prize season started Monday with laureates in Physiology or Medicine announced. This year's prize was awarded jointly to scientists William G. Kaelin Jr., Sir Peter J. Ratcliffe and Gregg L. Semenza for their discoveries of how cells sense and adapt to oxygen availability. Animals need oxygen for the conversion of food into useful energy. But how cells adapt to changes in levels of oxygen has long been unknown. Kaelin Jr., Ratcliffe and Semenza identified molecular machinery that regulates the activity of genes in response to varying levels of oxygen. The scientists established the basis for the process of how oxygen levels affect cellular metabolism and physiological function. Their discoveries also paved the way for promising new strategies to fight anemia, cancer and many other diseases, the Nobel Assembly at Karolinska Institute said. The groundbreaking work of the Nobel Laureates helped the medical world know much more about how different oxygen levels regulate fundamental physiological processes. Oxygen sensing allows cells to adapt their metabolism to low oxygen levels: for example, in human muscles during intense exercise. Oxygen sensing is vital to a number of diseases, including chronic renal failure, in which patients often suffer from severe anemia due to decreased EPO expression. The oxygen-regulated machinery has an important role in cancer. In tumors, the oxygen-regulated machinery is utilized to stimulate blood vessel formation and reshape metabolism for effective proliferation of cancer cells. Academic laboratories and pharmaceutical companies are now focused on developing drugs that can interfere with different disease states by either activating, or blocking the oxygen-sensing machinery. William G. Kaelin Jr., an American scientist, is an Investigator of the Howard Hughes Medical Institute. He established his own research lab at the Dana-Farber Cancer Institute and became a full professor at Harvard Medical School in 2002. British scientist Sir Peter Ratcliffe established an independent research group at Oxford University and became a full professor in 1996. He is the Director of Clinical Research at Francis Crick Institute, London, Director for Target Discovery Institute in Oxford and Member of the Ludwig Institute for Cancer Research. Gregg Semenza from New York is a professor at Johns Hopkins University and the Director of the Vascular Research Program at the Johns Hopkins Institute for Cell Engineering. The Nobel Prize in Physics will be announced on Tuesday.