Final answer:
The number of normal receptors in the plasma membranes of malignant cells typically decreases compared to normal cells, which can contribute to the unregulated growth characteristic of cancer.
Step-by-step explanation:
In comparison to normal cells, the number of normal receptors in the plasma membranes of malignant cells often decreases. This alteration in receptor number can affect how cells respond to signals such as hormones and can lead to unregulated cell growth and division, a hallmark of cancer. For example, cancer cells often fail to form proper cell-to-cell interactions due to defects in their plasma membranes, including changes in receptor numbers and types. Cancer cells may also fail to undergo negative feedback mechanisms that typically control cell growth, leading to their unchecked proliferation.