Furthermore, soluble DLK1 strongly enhanced the self-renewal ability of responsive glioma cell lines, as measured by the serial sphere-formation assay (Figure 4A−B) performed at clonal density (Supplementary Figure 3), and induced a significant increase in the stem cell markers OCT4, NANOG, and SOX2 (Figure 4C). This evidence concerns the gene POU5F1 and glioma.