GFAP and medulloblastoma: Furthermore, GFAP expression was preserved (Fig EV4A′′) as well as the loss of expression of H3K27me3 (Fig EV4A′′′), which, in the context of a PF ependymoma, is currently used in the pathology practice as a reliable surrogate marker for the molecular subgroup A. In the PDOs of tumor #9 (SHH MB) and PDOs of tumor #12 (G4 MB), coherently with the parental anaplastic medulloblastoma, mitoses, and apoptosis were easily identified, and the expression of synaptophysin was preserved (Fig EV4B).