Patient-derived GBM stem cells show usually strong expression of GFAP, Nestin, Sox-2, Musashi-1, Bmi-1 (Figure 3a), whereas no immuno-reactivity is observed with differentiated cell markers, such as Tuj1, NeuN, which are early and late neuronal markers, respectively, or Olig-1, which is specific for oligodendritic lineages (Figure 3b) [12,13]. The gene discussed is GFAP; the disease is glioblastoma.