NOTCH1 and cancer: TRAIL acts as an effector molecule of immune surveillance by various T-cell subpopulations, NK-cells and macrophages and is therefore important for the elimination of cancer cells by the immune system.50 Glioblastoma cells are furthermore also targeted by TRAIL expressed by reactive astrocytes.51, 52 Since high levels of Notch1 expression are a characteristic feature of glioblastomas,13 DR5 protein levels are constantly suppressed.