NF1 and neoplasm: Prior work experimentally comparing PN progression after bone marrow transplantation demonstrated that the Nf1+/- tumor microenvironment specifically promotes progression of PN.16 The present study and survival differences between genetic backgrounds are also consistent with a tumor extrinsic mechanism, possibly originating in the tumor microenvironment, contributing to the worse survival of male Nf1fl/- mice receiving 30 Gy SI.