ASCL1 and central nervous system cancer: ASCL1 is frequently expressed in malignant brain tumours, including oliogdendroglioma, diffuse astrocytoma and proneural type glioblastoma, as well as in primary glioblastoma and lower grade gliomas (Rheinbay et al., 2013; Rousseau et al., 2006; Somasundaram et al., 2005).