Nf1 periostin-Cre mice develop extensive spinal plexiform neurofibromas by 5 months of age.10 These plexiform neurofibromas rarely spontaneously transform to higher grade MPSNTs, however transformation can be promoted by loss of CDKN2A10 as well as p53 knockdown.11 These models recapitulate the spontaneous PN to MPNST progression that occurs in approximately 10% of individuals with NF1.12 This evidence concerns the gene POSTN and malignant peripheral nerve sheath tumor.