MAPK1 and schwannoma: Recent research on Nf2 gene showed that merlin is involved in different signal transduction pathways, including MAPK/ERK and Hippo pathways.5,6 Indeed, in merlin null schwannomas the MAPK/ERK pathway is activated,6 whereas the Hippo pathway is involved in several cell transformations,7 mostly through control of the transcriptional co-activator Yes-associated protein (Yap).8 Of note, Hippo has been indicated as a major effector of merlin in growth regulation,9 even though this correlation was poorly investigated in SCs.