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 growth 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. Recognize the normal function of proto-oncogenes: In their normal state, proto-oncogenes stimulate normal cell growth and division, ensuring that cells divide at the right time and in the right amount.
4. Clarify misconceptions: Proto-oncogenes do not suppress tumor growth; rather, they are involved in promoting normal cell growth. They are not typically underexpressed in cancer cells; instead, mutations can lead to overexpression or abnormal activity.
5. Connect to cancer biology: In cancer cells, proto-oncogenes can become oncogenes, leading to enhanced tumor growth due to the loss of regulation in cell division processes.