Abstract
The importance of oxygen to life has been recognized for hundreds of years, but how cells and tissues sense reduced oxygen levels remained elusive until the late twentieth century. The 2019 Nobel Prize in Physiology or Medicine was awarded to William G. Kaelin Jr., Sir Peter J. Ratcliffe, and Gregg L. Semenza for their discovery of hypoxia-inducible factor, a key transcription factor that regulates gene expression in response to decreases in cellular oxygenation. The three scientists provided the first information about the cellular oxygen-sensing mechanism and downstream signal transduction under hypoxic conditions. Their discoveries have also paved the way for promising novel treatments for cancer, renal anemia, and inflammatory disease.