While SOX2 is highly expressed in the proliferating populations of some brain tumors it has also been shown that SOX2-positive cells in brain tumors coexpress GFAP, indicating that SOX2 may serve as a selective marker of tumor cells deriving from or assigning to a glial lineage rather than a marker of all neoplastic cells (Phi et al., 2008). This evidence concerns the gene GFAP and brain neoplasm.