ASCL1 and neoplasm: Using PDX‐GBM lines (R548, R738), in which tumors from patients were passaged orthotopically in the brains of NOD‐SCID mice (Figure 1a) (Marian et al., 2010; Marin‐Valencia et al., 2012), we demonstrated that the transplanted tumors exhibit pathological characteristics of high‐grade gliomas (Figure 1b,c) and express ASCL1, OLIG2, and SOX2 in the majority of tumor cells (Figure 1d–m).