Which of the following is NOT a tumor suppressor gene?

Tumor suppressor genes are crucial in regulating cell growth and preventing tumor formation. They typically code for proteins that help control the cell cycle, repair DNA, and maintain genomic stability. When these genes are mutated or dysfunctional, cellular proliferation can occur unchecked, often leading to cancer.

BRCA1, P53, and PTEN are all well-established tumor suppressor genes. BRCA1 is involved in DNA repair processes and genome integrity; mutations can significantly increase the risk for breast and ovarian cancers. P53 plays a critical role in preventing cancer formation by regulating the cell cycle and triggering apoptosis in response to DNA damage. PTEN is involved in the regulation of the cell cycle and metabolism, promoting apoptosis and restraining cell growth when functioning correctly.

On the other hand, EGFR (Epidermal Growth Factor Receptor) is a receptor tyrosine kinase that, when activated, promotes cell proliferation and survival. While it can be overexpressed or mutated in many cancers, it does not function to suppress tumor growth like the other genes mentioned. This distinction makes EGFR the correct choice for the gene that does not fit the tumor suppressor category.