OLIG2 and central nervous system cancer: The prevalence of Olig2+ cells in human gliomas [5], coupled with recent findings that Olig2+ oligodendrocyte precursor cells (OPCs) are the cells of origin for murine malignant glioma [19], raises the possibility that OPCs might be another tumor-initiating cell population for Nf1 murine optic glioma.