A tumor suppressor is a type of protein that helps regulate cell growth and division, preventing the formation of tumors. These proteins act as a safeguard, ensuring that cells do not grow uncontrollably. When tumor suppressor genes are functioning properly, they can repair damaged DNA or trigger cell death if the damage is too severe. When tumor suppressor genes are mutated or lost, their protective effects diminish, leading to an increased risk of cancer. One well-known tumor suppressor gene is TP53, which produces the p53 protein, often referred to as the "guardian of the genome" for its role in maintaining cellular integrity.