GFAP and ependymoma: Although the WHO tumor grade classification is weakened nowadays for ependymomas [3], few proteins intriguingly exhibited a statistically significant variation between grade II (EP 1–3, 5) and grade III (EP 6–9, 11, 12) PF-EPs, all exhibiting increased levels in the tumor tissue of lower grade, namely, the alpha (HBA1) (p = 0.03) and the beta (HBB) (p = 0.01) hemoglobin subunits and the fragment 388–432 of GFAP (p = 0.04) (Figure 4).