As a byproduct of their rapid metabolism and growth, cancer cells frequently produce high levels of so-called free radicals–highly reactive particles that can damage cells. To protect themselves, cancer cells also produce antioxidants, which deactivate the free radicals. Drugs that block these antioxidants should therefore selectively impair cancer cells, while having relatively little effect on healthy cells that do not experience high levels of free radicals. Researchers found that the antioxidant-inhibiting drug ATN-224 induced the death of non-small lung cancer (NSCLC) cells in cell culture. ATN-224 also decreased the number and size of lung tumors in mice injected with NSCLC cells.