NF1 and neoplasm: These results are consistent with the known pathoetiology of PNs that (1) loss of function of the NF1 gene potentiates the Ras pathway signaling [39] and (2) Schwann cell progenitors can serve as the cell of origin of PN and subsequently recruit NF1-heterozygous non-neoplastic cells into the tumor microenvironment [38].