Jeremy N. Rich, MD (Damon Runyon-Lilly Clinical Investigator ‘04-‘09) of Cleveland Clinic, Cleveland, and colleagues, reported new findings about brain cancer stem cells. Malignant gliomas, aggressive brain tumors with limited treatment options, contain highly tumorigenic subpopulations of cancer stem cells. The researchers identified an enzyme, nitric oxide synthase-2 (NOS2), required for these stem cells to grow and seed tumors. High NOS2 levels correlate with decreased survival in patients with glioma. Drugs that block NOS2 slow brain tumor growth in mice. Scientists hope these findings will enable glioma stem cells to be targeted in humans, providing an effective new treatment option. This study was published in the scientific journal Cell.