What turns a normal cell into a cancer cell? Scientists have long suspected that the answer lies somewhere in the chromosomal material. This is based on the observation that once a normal cell becomes cancerous, through a process called malignant transformation, it passes its tumor characteristics on to progeny in a stable manner. In addition, most carcinogens have also been shown in the laboratory to damage DNA.
The recent finding that certain single genes present in normal cell DNA, called cellular oncogenes, have the potential to trigger cell transformation has given researchers a new focus for study (JAMA 1982; 247:178-181;1098-1103). Some of these genes appear to play an active role in normal cell function. Yet in tumor cells they have somehow been altered in a way that results in cancer. What sort of DNA changes are involved in this alteration?
For at least one type of oncogene, researchers now have