GFAP and ependymoma: In detail, tumor #2 (PF ependymoma Group A) still presented GFAP+ glial cells and was negative for OLIG2 progenitor cells marker (Fig EV4D and E); tumor #9 (SHH MB) was negative for GFAP (the GFAP+ cells were interpreted as resident mouse astrocytes since those are human nuclear antigen‐), positive for OLIG2 and presented also SOX9 positive glial precursors cells (Vong et al, 2015; Sun et al, 2017) (Fig EV4F–H).