AQP1 and neoplasm: These different populations of ependymoma-CSCs (with a radial glia cell phenotype) had self-renewal abilities and were multipotent in culture; additionally, they also had anatomic site-specific chromosomal alterations or expression signatures, such as Ephrin type B receptor 2/3/4 (EPHB2/3/4), Ephrin A3/4, Jagged1/2 (JAG1/2) in supratentorial tumours, an inhibitor of a differentiation family of proteins 1/2/4 (ID1/2/4), AQP1/3/4 in anteroposterior tumours, and Homeobox (HOX) in spinal tumours [33], later confirmed by the single-cell RNA sequencing technique.