Which characteristic is NOT associated with tumor suppressor genes?

Tumor suppressor genes play a crucial role in regulating cell division and maintaining the integrity of the cell cycle. They act as inhibitors of cancer progression by coding for proteins that can repair DNA, regulate cell growth, and induce apoptosis in cells that are damaged or no longer needed. When these genes are functioning properly, they help prevent the formation of tumors.

The characteristic that is not associated with tumor suppressor genes is their promotion of uncontrolled cell division. Such behavior is more typical of oncogenes, which are genes that, when mutated or expressed at high levels, drive the proliferation of cancer cells. In contrast, tumor suppressor genes are designed to prevent abnormal growth; thus, when they are deficient or mutated, the regulatory mechanisms they provide are lost, potentially leading to tumor formation.

The requirement for both alleles to be mutated for inactivation (the "two-hit hypothesis") reflects the way many tumor suppressor genes function. Typically, a single functional copy of a tumor suppressor gene can be sufficient to carry out its inhibitory role, further emphasizing why promoting uncontrolled cell division is not a characteristic associated with them.