A gene produces a protein that evidently protects cancer cells in the same way it shields brain cells from damage caused by diseases like Alzheimer’s and strokes. “The same substance can be doubly harmful to some people with invasive breast cancer because it protects the tumor cells from death,” notes Kornelia Polyak, an assistant professor of medicine at Harvard Medical School. Fragments of this Janus-like protein, dubbed dermcidin or DCD, have also been found in the blood of people with cachexia, a muscle-wasting disease that afflicts some terminally ill cancer patients. Such revelations have excited a number of drug companies about the potential uses of DCD. Since Polyak and her colleagues published their findings in September 2003 in the Proceedings of the National Academy of Science, several drug companies have contacted them about the possibility of using DCD as a means of diagnosing invasive breast cancer, the most common form of the malignancy.