Tumor suppressor genes regulate mitosis and cell division. When their function is impaired, the result is a high rate of uncontrolled cell growth or cancer. Damage to tumor suppressor genes contributes to a large number of different types of tumors.

The Balancing Act of Regulating the Cell Cycle

The cell cycle is a fundamental process of life, regulated by a balance of positive and negative mechanisms that act at key points during cell growth and differentiation. Proto-oncogenes tend to "push" the cell cycle (in a positively acting manner) by activating various cell cycle pathways within the developing cell. By contrast, tumor suppressor genes normally repress, or "put the brakes on," the activation of the pathways.

Genetics of Tumor Suppressor Genes

Mutations in tumor suppressor genes can arise spontaneously by exposure to a mutagenic substance such as ultraviolet light or certain chemicals. In such cases...