In vivo experiments taking advantage of cell‐specific expression of the Cre recombinase, demonstrated that not only NSC [149] but also Ascl1+ adult bipotential (neural and oligodendrocyte) progenitors and Ng2+ adult OPC [150] led to glioma formation when the tumour suppressor Nf1, Trp53, or Pten were inactivated. The gene discussed is PTEN; the disease is central nervous system cancer.