POU5F1 and glioblastoma: Consistent with these results, incubating GSC-containing neurospheres from DBTRG-05MG GBM cells in GBMpt1CAF CM for 24 hours increased the expression of GSC genes Nanog (6.7-fold, P = 0.009), Sox2 (5.0-fold, P < 0.001), and Oct4 (3.0-fold, P = 0.005) (Supplemental Figure 20).