John Michael Bishop (born February 22, 1936) is an American immunologist and microbiologist. Bishop is best known for his Nobel-winning work on retroviral oncogenes. Working with Harold E. Varmus in the 1980s, he discovered the first human oncogene, c-Src. Their findings allowed the understanding of how malignant tumors are formed from changes to the normal genes of a cell. These changes can be produced by viruses, by radiation, or by exposure to some chemicals. The shared the Nobel Prize in Physiology or Medicine in 1989.