Oncogene was first identified in
**Core Concept**
The discovery of oncogenes is crucial in understanding cancer development and progression. Oncogenes are genes that have the potential to cause cancer when mutated or overexpressed. They can be derived from normal cellular genes, known as proto-oncogenes, which play a role in promoting cell growth and division.
**Why the Correct Answer is Right**
The first oncogene was identified in the Rous sarcoma virus (RSV), a retrovirus that causes cancer in chickens. The oncogene, known as src, was found to be responsible for the transformation of normal cells into cancerous cells. The src oncogene encodes a protein tyrosine kinase that plays a crucial role in signaling pathways involved in cell growth, differentiation, and survival. When mutated or overexpressed, the src oncogene can lead to uncontrolled cell growth and tumor formation.
**Why Each Wrong Option is Incorrect**
**Option A:** While the discovery of oncogenes is closely related to the development of cancer, it is not accurate to say that the first oncogene was identified in the human genome. The human genome is a vast and complex entity, and the discovery of oncogenes was facilitated by the study of viruses and other pathogens.
**Option B:** The Epstein-Barr virus (EBV) is a human herpesvirus that is associated with several types of cancer, including Burkitt lymphoma and nasopharyngeal carcinoma. However, it was not the first oncogene to be identified.
**Option C:** The human papillomavirus (HPV) is a group of viruses that are associated with several types of cancer, including cervical cancer and oropharyngeal cancer. While HPV is an important oncogenic virus, it was not the first to be identified.
**Clinical Pearl / High-Yield Fact**
The discovery of oncogenes has led to a greater understanding of the molecular mechanisms underlying cancer development and progression. This knowledge has paved the way for the development of targeted therapies, which can selectively inhibit the activity of oncogenes and prevent tumor growth.
**Correct Answer: A. Rous sarcoma virus.**