NF2 and schwannoma: The pathways implicated in schwannoma tumorigenesis are the loss of Merlin-mediated inhibition of the MAP kinase MEK/ERK cascade), and the PI3K/mTOR signaling pathways (phosphatidylinostitol-3 kinase (PI3K)/serine-threonine protein kinase/Akt cascade/mTOR/p70S6K).