Final answer:
The loss of the tumor suppressor gene APC can lead to colon cancer, as it plays a key role in cell cycle regulation by repairing DNA damage and initiating apoptosis. Mutations in p53 also contribute to cancer development due to its essential role as a tumor suppressor.
Step-by-step explanation:
A loss of APC leads to colon cancer (due to turning off tumor suppressors via hypermethylation). The primary function of tumor suppressor genes like APC is to regulate cell growth by monitoring and repairing DNA damage or initiating apoptosis to prevent the proliferation of cancerous cells. Mutations in p53, which is a well-known tumor suppressor, are associated with many human cancers, indicating its crucial role in protecting cells from becoming cancerous. Mutated p53 genes fail to detect or repair damaged DNA and cannot trigger apoptosis, leading to the development of cancer. Therefore, the loss of tumor suppressor genes like APC and mutations in genes like TP53 that code for p53 are associated with increased cancer risk.