In the healthy central nervous system, nestin is expressed by neural progenitor/stem cells, but not by differentiated neurons and glial cells.28,29 Nestin has been used as a marker for glioma stem cells in glioblastomas.23 More work is needed to quantify the proportion of IDH1 cells that are PpIX+ and nestin+. Here, IDH1 is linked to central nervous system cancer.