What defines an oncogene?

An oncogene is a gene that has mutated and is associated with the promotion of cancer. Normally, genes that regulate cell growth and division can do so properly; however, when they undergo mutations, they can contribute to uncontrolled cell division, leading to tumor formation. These mutations can result from various factors, such as exposure to carcinogens, viral infections, or inherited genetic predispositions.

When a proto-oncogene, the normal counterpart of an oncogene, experiences a mutation that alters its function, it can become an oncogene. This change may increase the production of proteins that encourage cell growth and division, or it can lead to the production of abnormal proteins that disrupt the regulatory mechanisms of the cell. This ability of oncogenes to promote excessive cell proliferation is a crucial aspect of cancer development.