Each of the following can contribute to proliferation of cancer cells except:

A. tumor-suppressor inactivation.

B. inhibition of apoptosis.

C. density-dependent inhibition of growth.

D. All can contribute to immortalization.

Answer: C) density-dependent inhibition of growth.

Explanation:

Cancer cells divide rapidly and grow in number abnormally at a rapid rate. These cells are poorly differentiated and they have abnormal membranes, morphology and cytoskeletal proteins.

In density dependent inhibition the cell growth is inhibited and the density of the cells becomes low. The cancerous tumor cells usually loose the density-dependent inhibition.