Table 7.1.

Categories of Oncogenes

Type	Example
Extracellular growth factors (homologs of normal growth factors)	c-sis: Encodes the platelet-derived growth factor (PDGF) B chain (v-sis in simian sarcoma virus) int-2: Encodes a fibroblast growth factor (FGF)-related growth factor (common site of integration for mouse mammary tumor virus)
Receptor tyrosine kinases (associated with the inner surface of the cell membrane)	c-fms: Encodes the colony-stimulating factor 1 (CSF-1) receptor; first identified as a retrovirus oncogene c-kit: Encodes the mast cell growth factor receptor
Membrane-associated nonreceptor tyrosine kinases (signal transduction)	c-src: v-src was the first identified oncogene (Rous sarcoma virus) lck: Associated with the CD4 and CD8 antigens of T cells
G-protein-coupled receptors (signal transduction)	mas: Encodes the angiotensin receptor
Membrane-associated G-proteins (signal transduction)	c-ras: Three different homologs of c-ras gene, each identified in a different type of tumor and each transduced by a different retrovirus
Serine/threonine kinases (signal transduction)	c-raf: Involved in the signalling pathway; responsible for threonine phosphorylation of mitogen-activated protein (MAP) kinase following receptor activation
Nuclear DNA-binding/transcription factors	c-myc (v-myc in avian myelocytomatosis virus): Sarcomas caused by disruption of c-myc by retroviral integration or chromosomal rearrangements c-fos (v-fos in feline osteosarcoma virus): Interacts with a second proto-oncogene protein, Jun, to form a transcriptional regulatory complex