Neural stem cells (NSC) were engineered to secrete the potent tumoricidal cytokine interleukin 12 (IL-12). When transplanted into established murine intracranial brain tumors, NSC were found to disseminate widely and exhibited specific tropism for tumor outgrowths and microsatellites. IL-12- secreting NSC therapy significantly prolonged survival in brain tumor- bearing rodents. The illustration demonstrates an astrocytic culture positive for glial fibrillary acidic protein (GFAP) derived from primary NSC. A neurosphere (comprising of NSC) is visible in the inset box and is stained positive for the neural progenitor marker, nestin (red), with nuclei counterstained with DAPI (blue). For details, see the article by Ehtesham et al. on page 5657 of this issue.