Growth factor oncogen is –
**Core Concept**
The question is testing the student's understanding of oncogenes, specifically those that encode growth factors. Growth factor oncogenes are a class of proto-oncogenes that encode proteins involved in cell growth, proliferation, and survival. When mutated or overexpressed, these oncogenes can lead to uncontrolled cell growth and cancer.
**Why the Correct Answer is Right**
The correct answer is a growth factor oncogene that encodes a protein involved in cell growth and proliferation. This protein binds to its receptor on the cell surface, triggering a signaling cascade that promotes cell growth and survival. The mutation or overexpression of this oncogene can lead to the formation of a constitutively active protein that continuously signals for cell growth, even in the absence of its ligand.
**Why Each Wrong Option is Incorrect**
* **Option A:** This is incorrect because it does not encode a growth factor, but rather a protein involved in cell cycle regulation.
* **Option B:** This is incorrect because it encodes a protein involved in DNA repair, not cell growth.
* **Option C:** This is incorrect because it is a tumor suppressor gene, not an oncogene.
**Clinical Pearl / High-Yield Fact**
Growth factor oncogenes are a common class of oncogenes found in various types of cancer. They often result from mutations that lead to the formation of constitutively active proteins that continuously signal for cell growth. Understanding the role of growth factor oncogenes is crucial for developing targeted therapies for cancer treatment.
**Correct Answer:** C.