THURSDAY, July 20 (HealthDay News) -- Researchers say they're gaining greater insight into how the brain's own stem cells may trigger one of the deadliest forms of cancer. The stem cells -- which can turn into a variety of brain cells -- appear to carry a receptor that pulls in a specific chemical. If the cells get over-stimulated by the chemical, that may lead to tumor formation. The discovery, "might lead to better understanding of early growth" of brain malignancies, said study co-author Arturo Alvarez-Buylla, a professor of neurological surgery at the University of California, San Francisco. As a result,...