Radioresistance of glioma stem cells: Intrinsic characteristic or property of the 'microenvironment-stem cell unit'?

► Microenvironmental factors strongly influence both glioma stem cell biology and cellular radiation responses. ► Such factors may explain the inconsistency of in vitro data describing intrinsic radiation responses of glioma stem cells. ► Components of the glioblastoma microenvironment that modulate radiation sensitivity are potential therapeutic targets.