KLF4 and glioblastoma: Cells in GBM express OCT-4 (104, 105), SOX2 (1, 104, 114), pSTAT3 (81, 134), NANOG (104, 152), SALL4 (80, 99), c-Myc (78, 168, 172), KLF4 (58, 190), nestin (20, 21), CD44 (239, 240), CD133 (21, 218), and GFAP (207, 208), highlighting an overlapping hierarchical and heterogeneous population of stem and progenitor cells within GBM.