Their role in ependymoma development was validated by overexpressing EphB2 in supratentorial E14.5 neural stem cells (STeNSCs) (previously identified as the potential cell of origin for ependymoma36) deleted of the Ink4a/ARF locus and implanting these cells in recipient mice brains proximal to the third ventricle. The gene discussed is EPHB2; the disease is ependymoma.