All of the following are tumor suppressor genes except: September 200
**Core Concept**
Tumor suppressor genes are a class of genes that encode proteins responsible for regulating cell growth, preventing uncontrolled cell division, and promoting apoptosis when necessary. They act as brakes on the cell cycle to prevent cancer development.
**Why the Correct Answer is Right**
The correct answer will be a gene that is not involved in tumor suppression but rather has a different function. Tumor suppressor genes typically encode proteins that are involved in DNA repair, cell cycle regulation, or apoptosis. For example, the TP53 gene is a well-known tumor suppressor that encodes the p53 protein, which prevents cancer by repairing DNA damage and initiating apoptosis when necessary.
**Why Each Wrong Option is Incorrect**
**Option A:** The TP53 gene is a tumor suppressor gene that encodes the p53 protein, which is involved in DNA repair and apoptosis.
**Option B:** The RB1 gene is a tumor suppressor gene that encodes the retinoblastoma protein, which regulates the cell cycle and prevents uncontrolled cell division.
**Option C:** The BRCA2 gene is a tumor suppressor gene that encodes a protein involved in DNA repair and maintenance of genome stability.
**Option D:** The HER2 gene is an oncogene that encodes a protein involved in cell growth and proliferation, but not a tumor suppressor.
**Clinical Pearl / High-Yield Fact**
Tumor suppressor genes are frequently mutated in various types of cancer, leading to loss of their normal function and contributing to cancer development. Understanding the functions of tumor suppressor genes is crucial for developing targeted cancer therapies.
**Correct Answer:** D. HER2 gene.