When the tumor proliferation rate was measured at the protein level in either GBM tissues or in their derivative GSCs by counting the cells positive for the proliferation markers Ki67 and MELK, TCGA-CL samples were confirmed to propagate more extensively than tumors and cells from either TCGA-MS or TCGA-PN subtype (Supplementary Fig. 4A, B). Here, MELK is linked to neoplasm.