Which of the following is not a characteristic feature of cancer cells?

Options

A. abundance of telomerase enzyme
B. loss of contact inhibition
C. uncontrolled proliferation
D. presence of unaltered proto-oncogenes

Answer

To determine which of the following is not a characteristic feature of cancer cells, we will analyze each option based on the known properties of cancer cells.

### Step-by-Step Solution:

1. **Understanding Cancer Cell Characteristics**:
- Cancer cells have specific features that differentiate them from normal cells. These include mechanisms that allow them to grow uncontrollably, evade death, and spread to other parts of the body.

2. **Analyzing Option 1 - Abundance of Telomerase Enzyme**:
- Cancer cells often exhibit high levels of the telomerase enzyme. This enzyme adds telomeres to the ends of chromosomes, preventing them from shortening during cell division. This characteristic allows cancer cells to avoid the normal aging process and continue dividing indefinitely.

3. **Analyzing Option 2 - Loss of Contact Inhibition**:
- Normal cells stop growing when they come into contact with neighboring cells, a phenomenon known as contact inhibition. Cancer cells lose this property and can continue to grow and pile up on each other, leading to tumor formation.

4. **Analyzing Option 3 - Uncontrolled Proliferation**:
- Cancer cells proliferate uncontrollably, which is a hallmark of cancer. This uncontrolled growth leads to the formation of tumors.

5. **Analyzing Option 4 - Presence of Unaltered Proto-oncogenes**:
- Proto-oncogenes are normal genes that can become oncogenes due to mutations or alterations. In cancer, these genes are often mutated or altered, leading to uncontrolled cell growth. Therefore, the presence of unaltered proto-oncogenes is not a characteristic feature of cancer cells.

6. **Conclusion**:
- Based on the analysis, the statement that is not a characteristic feature of cancer cells is the "presence of unaltered proto-oncogenes." Thus, the correct answer is **Option 4**.