NF2 and meningioma: For grade I meningiomas, mutations in AKT1 (v-akt murine thymoma viral oncogene homolog 1, leading to activation of the PI3K pathway), TRAF7 (Tumor necrosis factor receptor-associated factor 7, encoding the pro-apoptotic E3 ubiquitin ligase), KLF4 (Krupple-like factor 4, a pluripotency-inducing transcription factor) and SMO (Smoothened, frizzled family receptor, leading to activation of the Hedgehog pathway) have been identified and appear to be mutually exclusive of NF2 alterations (22).