VRK1 and glioblastoma: Similarly, VRK2 overexpression in VRK2lo GBM lines and primary DMG neurospheres rescued VRK1 dependency, which required VRK2 kinase activity, as expression of the kinase-inactive VRK2K168E mutant did not rescue VRK1 KO–induced cell death (Figure 2, G–I; and Supplemental Figure 6, D–H).