NF1 and malignant peripheral nerve sheath tumor: Loss of NF1 activity leads to activation of RAS and consequently contributes to the PI3K/AKT/mTOR and RAF/MEK/ERK signaling in MPNST (Ågesen et al., 2005; Berner et al., 1999; Brems et al., 2009; Danielsen et al., 2015; Endo et al., 2013; Nielsen et al., 1999).