POU5F1 and glioblastoma: Depending on the preparation, the mRNA expression of SKI, H2BK, Nestin, MSI1, and SOX2 (first GBM cell preparation), as well as OCT4, MSI1, and IGFBP5 (second preparation), was particularly well regulated in this experimental setting (no separate analysis of the focal and peri-focal region, as methodologically not possible).