Which of the following processes do normal proto-oncogenes typically exhibit?

• A. They normally suppress tumor growth.
• B. They enhance tumor growth.
• C. They stimulate normal cell growth and division.
• D. They are underexpressed in cancer cells.

Answer: (C)

Verified step by step guidance

1. Understand the role of proto-oncogenes: Proto-oncogenes are genes that normally help cells grow. They are essential for normal cell function and division.
2. Differentiate between proto-oncogenes and oncogenes: When proto-oncogenes mutate, they can become oncogenes, which may lead to uncontrolled cell growth and potentially cancer.
3. Identify the normal function of proto-oncogenes: In their normal state, proto-oncogenes stimulate normal cell growth and division, ensuring that cells proliferate as needed for healthy tissue maintenance and repair.
4. Clarify the misconception about tumor suppression: Proto-oncogenes do not suppress tumor growth; rather, they promote normal cell growth. Tumor suppressor genes are responsible for inhibiting cell division and preventing tumor formation.
5. Recognize the expression levels in cancer cells: In cancer cells, proto-oncogenes may be overexpressed or mutated, leading to enhanced cell growth and division, contributing to tumor development.