Cellular Oncogenes

Oncogenes (tumor-causing genes) were originally
identified in RNA tumor viruses (retroviruses)
as genes (v-onc) that could transform
cells into an altered state of control of cell proliferation,
often resulting in a tumor, mainly in
chicken, mice, and rats. More than 20 different
viral oncogenes are known to have a counterpart
in normal cells (c-onc), called proto-oncogenes
or cellular oncogenes. These cellular
genes are highly conserved in evolution because
they have important functions in all
eukaryotic cells. They encode proteins that are
required at defined sites throughout the cell
where they regulate the ordered progression
through the cell cycle, cell division, and differentiation.