OLIG2 and glioblastoma: Arsenic trioxide and 10058F4 co-treated mice but not mono-treated mice exhibited drastic reduction of Olig2-positive proneural GBM CSCs and CD44-positive mesenchymal GBM CSCs [25–27] and enhanced differentiation to TujI-positive cells (Olig2: P = 0.027, CD44: P = 0.0075, TujI: P = 0.00093) (Fig 8A and 8B).