TP53 and malignant peripheral nerve sheath tumor: It is thus highly likely that TP53, CDKN2A and PTEN are driver genes in 2XSB cells and that dysregulation of the cell cycle and phosphatidylinositol 3-kinase (PI3K) signaling played an important role in the development of this sporadic MPNST, much as it does in NF1-associated MPNSTs.