Harold Varmus was born in 1933 in Long-Island, USA. He studied at the University of California, at San-Francisco where he became professor of biochemistry and biophysics in 1982.

In 1989, the Nobel prize in physiology and medicine was awarded to Harold Varmus and Michael Bishop “for their discovery of the cellular origin of retroviral oncogenes”.

Varmus conducted his research on the cancerous factor sarcoma (RSV) and found a gene that causes cancer. Surprisingly, he discovered the presence of this gene in the genome of healthy birds and mammals.

Varmus concluded that the active gene, in the oncogene virus, comes from cellular genes whose normal function is to control cell growth, division and differentiation. At some point of its evolution, the RSV virus extracts a gene from the host genome and inserts it into its own genome. Thus, this cellular gene undergoes changes that allow it to convert an infect cell into a cancerous cell.

Further study revealed that this cellular gene can be transformed into an oncogene even without viral contact and prevent the cell from going through normal differentiation.

Since the discovery of Varmus and Bishop in 1976, more than 50 cellular genes with the potential to become oncogenes have been identified.