GAP43 and plexiform neurofibroma: Importantly, tumor initiation may also be influenced by the germline Nf1 mutation acting on the tumor cells of origin51, requiring investigations of the impact of the NF1 Arg1809Cys mutation on third ventricle neural progenitors (OPG)52 and Sox10+, GAP43+ Schwann cell precursors (neurofibroma)48–50,53.