Again and again, recent studies of cancer genetics have revealed that what once appeared to be a single disease -- such as breast or lung cancer -- is really a mosaic made up of many different subtypes, each with its own genetic roots that may require its own targeted therapy.

Now scientists working independently in Boston and Germany have made a surprising discovery: a set of genetic mutations found in most melanomas, the deadliest skin cancer. The presence of these mutations in the vast majority of tumors studied suggests that the researchers may have stumbled upon a fundamental mechanism involved in a hallmark trait of cancer cells -- their ability to live forever -- a mechanism that could one day be targeted by drugs.