Viruses, genes, and cancer. I. The discovery of cellular oncogenes and their role in neoplasia
Using a blend of biochemistry and genetics, a host of investigators showed that each virus particle contained two identical subunits, each with three coding regions required for replication of the virus and one for its oncogenic capacity. The three replication functions (gag for core proteins, pol for reverse transcriptase, and env for envelope glycoproteins) play no direct role in formation of tumors or transformation of cultured cells to a neoplastic phenotype. Conversely, the viral oncogene (src) is fully dispensable for virus growth, but required continuously for the oncogenic state.