As the majority of astrocytomas are preferentially located in areas rich in neural progenitor cells (Chow et al., 2011; Zong et al., 2015), the tumour-initiating capacity of astrocytes has been difficult to assess, as they co-express markers of neural precursor cells (e.g. GFAP). This evidence concerns the gene GFAP and astrocytoma (excluding glioblastoma).