Matthew Septimus (photographer) · CC BY-SA 4.0

Varmus shared the 1989 Nobel Prize in Physiology or Medicine with J. Michael Bishop for discovering that cancer-causing genes carried by retroviruses actually originate in normal cellular genes, a finding that reoriented cancer research around the idea that tumors arise from the malfunction of genes every cell already carries. He went on to direct the National Institutes of Health under President Clinton and, decades later, the National Cancer Institute under President Obama, moving between laboratory science and the leadership of American medical research.