NF1 and malignant peripheral nerve sheath tumor: Of a total of 1,409 somatic mutations identified in the four primary tumors, only 6 (3 in MPNST-NF1-002-OT1 and 3 in MPNST-NF1-001-OT4) were not detected in the orthotopic xenograft models and therefore classified as lost in the engraftment process (data not shown).