POU5F1 and glioblastoma: We have previously utilized a plasmid with the promoter for the human Oct3/4 gene tagged with a GFP reporter (phOCT4p-eGFP) and demonstrated its use to identify undifferentiated self-renewing hES [15], isolate tumorigenic cells from osteosarcoma cell populations [16], and highlight the role of Oct3/4 in regulating stemness in CSCs and tumor initiation in Glioblastoma (GBM) [17].