MTOR and osteosarcoma: ASleeping Beauty (SB) transposon-based forward genetic screen was performed in mice with and without somatic loss ofTrp53 to identify common insertion sites associated with the development of osteosarcoma.Pten was one of the most commonly mutated genes in both Trp53-SB-mutated and non-Trp53-SB-mutated tumors.Nf2 andNf1, both of which serve regulatory functions for downstream mTOR signaling, were also frequently mutated in the SB-mutated tumors.