PIK3CB and pilocytic astrocytoma: Figure 1A shows examples of IHC staining with PI3K p110α, EGFR, S6, and p-S6 (S235/236) on two TMA positions, representing stainings of a WHO grade I pilocytic astrocytoma and a WHO grade IV glioblastoma and indicating increased expression of all antigens shown in case of GBM.