v-Src is agene found inRous sarcoma virus (RSV) that encodes atyrosine kinase that causes a type of cancer in chickens.

Thesrc gene isoncogenic as it triggers uncontrolled growth in abnormal host cells. It was the first retroviral oncogene to be discovered.^[1] The src gene was taken up by RSV and incorporated into itsgenome^[2] conferring it with the advantage of being able to stimulate uncontrolledmitosis of host cells, providing abundant cells for freshinfection.

The src gene is not essential for RSVproliferation but it greatly increasesvirulence when present.

Francis Peyton Rous first proposed that viruses can cause cancer. He proved it in 1911 and was later awarded the Nobel prize in 1966. Chickens grow a tumor called afibrosarcoma. Rous collected and ground up thesesarcomas, and then centrifuged them to remove the solid material. Next, the remaining liquid mixture was injected into chicks. The chicks developed sarcomas. The causative agent in the liquid was a virus, this is now called the Rous sarcoma virus (RSV).

Further research done later on by others showed that RSV was a type ofretrovirus. It was found that thev-Src gene in RSV is required for the formation of cancer.^[3]

A function for Src tyrosine kinases in normal cell growth was first demonstrated with the binding of family member p56lck to the cytoplasmic tail of the CD4 and CD8 co-receptors on T-cells.^[4] Src tyrosine kinases also transmitintegrin-dependent signals central tocell movement andproliferation. Hallmarks of v-Src induced transformation are rounding of the cell and the formation of actin richpodosomes on the basal surface of the cell. These structures are correlated with increased invasiveness, a process thought to be essential for metastasis.

v-Src lacks theC-terminal inhibitory phosphorylation site (tyrosine-527), and is therefore constitutively active as opposed to normal Src (c-Src) which is only activated under certain circumstances where it is required (e.g. growth factor signaling). v-Src is therefore an instructive example of anoncogene whereas c-Src is aproto-oncogene.

The first sequence of v-Src was published in 1980^[5] and the characterization of sites for tyrosine phosphorylation in the transforming protein of Rous sarcoma virus and its normal cellular homologue was published in 1981.^[6]

• c-Src

• Oncogenes

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