Mutations, DNA Repair, and Cancer

In some cases, a mutation causes a gene to be overactive – have an abnormally high level of expression. This overactivity contributes to the uncontrolled cell growth that is observed in cancer cells. This type of mutant gene is called oncogene. A large number of oncogenes encode proteins that function in signal transduction pathways involved in cell growth.
How does an oncogene promote cancer? In some cases, an oncogene may keep a signal transduction pathway for cell division in a permanent “on” state. One-way oncogenes keep cell division turned on is by producing a functionally overactive protein.
A proto-oncogene is a normal gene that, if mutated, can become an oncogene.
A sarcoma is a tumor of connective tissue such as bone or cartilage.
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