TEK and glioblastoma: This key finding is the focus of this replication study.The authors transduced glioblastoma neurospheres with a lentiviral vector containing theherpes simplex virus thymidine kinase gene (tk) under the control ofthe transcription regulatory elements of the endothelial marker Tie2.In this way, the tumor-derived endothelial cells could be selectively killed by exposureto ganciclovir.