Analysis of DLK1 expression in the Cancer Genome Atlas (TCGA [21]), in the Chinese Glioma Genome Atlas (CGGA [22]) datasets and evaluation of DLK1 stainings in low- vs high-grade murine tumors revealed higher DLK1 expression in high-grade gliomas, that typically have hypoxic areas (Fig. 1i and Supplementary Fig. 1). The gene discussed is DLK1; the disease is glioma.