Tumor suppressor genes: a key to the cancer puzzle?

The molecular basis of cancer causation, to this date, is still poorly understood. Although numerous carcinogens have been identified (review in Oppenheimer 1985; 1987a; 1987b), the mechanism(s) of their action remains uncertain. In recent years indirect evidence has accumulated that suggested that these carcinogens act at the DNA level, altering or activating certain genes to form oncogenes (cancer causing genes), that can produce protein products that lead to the malignant transformation of cells.