CDKN2A and malignant peripheral nerve sheath tumor: As NF1-associated MPNST progress from NF1-nullizygous PN, they acquire mutations in other driver genes (e.g. TP53 and CDKN2A). NF1 loss is seen in a majority of sporadic MPNST, suggesting that NF1 is an important tumor suppressor in all MPNST.