NF1 and malignant peripheral nerve sheath tumor: MPNSTs are an aggressive subtype of soft tissue sarcoma that arise from the myelinating nerve sheath of peripheral neurons following loss of key tumor suppressor genes including neurofibromin 1 (NF1) and p53. Loss of Nf1 is a hallmark of MPNST biology, and is required for MPNST development in our model and other transgenic MPNST mouse models13–19.