Gliomas are among the most difficult cancers to treat, generally carrying a poor prognosis. One feature of its pathophysiology is glutamate release, which, through toxic effects on local brain cells, helps create spaces for tumor expansion. In their report, Lyons and colleagues offer evidence that glutamate also provides an essential signal for tumor cell invasion. Through knowledge about the mechanism of glutamate release, which involves a cell surface exchange system known as system x_c, they determined that the clinically approved drug sulfasalazine, a system x_c inhibitor, could limit tumor growth and invasion. These findings prompt clinical evaluation of sulfasalazine for glioma therapy. For details, see the article by Lyons and colleagues on page 9463 of this issue.