Final answer:
The most common oncogene in human tumors is the TP53 gene, known for encoding the tumor suppressor protein p53. This protein is crucial in repairing damaged DNA and, when mutated, is implicated in many cancers. Other important oncogenes, like HER2 and myc, also contribute to cancer by fostering uncontrolled cell growth.
Step-by-step explanation:
The most common oncogene in human tumors is the TP53 gene, which encodes the protein p53. This protein plays a crucial role in detecting and repairing damaged DNA, and thus acts as a tumor suppressor. Mutations in the TP53 gene are associated with a variety of human cancers, such as pancreatic, lung, renal cell, and breast cancers. In particular, mutated p53 genes are found in as many as half of human cancers. People with Li-Fraumeni syndrome (LFS), who have at least one mutated p53 allele, have a significantly increased risk of cancer, starting from childhood.
Cancer biologists have also identified other oncogenes that contribute to cancer development. For example, the HER2 oncogene encodes a cell-surface receptor that, when overexpressed due to gene duplication, contributes to 20 percent of human breast cancers. Drugs like Herceptin (trastuzumab), which target HER2, have been developed to harness the immune system to fight cancer, demonstrating the importance of these discoveries in treatment advancements.
Proto-oncogenes, when mutated, can become oncogenes and lead to uncontrolled cell growth and cancer. An example of such an oncogene is myc, which is a transcription factor that becomes aberrantly activated in Burkett's Lymphoma. These overexpressed oncogenes can transform normal cells into cancerous ones, resulting in rapid and unchecked cell proliferation.