Given the elevated frequency of MPNSTs (10%–13% adults3) and their younger age of onset (~3rd decade of life4,5), NF1 has emerged as a tractable model system to define the molecular etiologies for MPNST pathogenesis, as these cancers most often arise from benign precursor lesions (plexiform neurofibromas) with biallelic NF1 gene inactivation. This evidence concerns the gene NF1 and cancer.