SOX2 and central nervous system cancer: While the mRNA levels of genes related to pluripotency (SOX2, KLF4, MYC and NOTCH1) were not obviously correlated with the clinical glioma grade or outcome, the mRNA level of POU5F1, which also plays a crucial role in PGC specification, was often linked to a higher glioma grade and poor outcome (Fig. 3A, B, 4A, C, D and Additional file 1: Fig. S6A, Table S3–S5).