Varmus, Harold Elliot (1939– )

US molecular biologist who was awarded a Nobel Prize for Physiology or Medicine in 1989 with John Michael Bishop for the discovery of oncogenes, genes carried by viruses that can trigger cancerous growth in normal cells. Varmus's work showed that a single viral gene is sufficient to transform a cell into a cancerlike cell, and that this gene is also present in normal mammalian cells. Since the discovery of the first oncogene, many more have been found and used in cancer research.

The Rous sarcoma, or avian sarcoma virus, produces highly malignant tumours in chickens. Varmus and Bishop demonstrated that when the gene src is introduced into cells by this virus, it transforms the cell into a cancer-like cell. They also demonstrated, using DNA hybridization experiments, that the src gene was present, albeit usually in a quiescent form, in healthy mammalian cells.

Varmus was born in Oceanside, New York, and educated at Amherst College, Massachusetts, Harvard University, and Columbia University, where he received an MD. Since 1970 he has worked at the Medical Center of the University of California. He is the director of the US National Institutes of Health.