KDR and osteosarcoma: Studies demonstrated that MDM2 amplification [21], overexpression of VEGFR and PDGFR [22], the activation of mTOR [23], increase of IGF-1R [24], cyclin-dependent kinase [25], Aurora-B [26], TP53 [27] and MYC [28] were associated with the metastasis of osteosarcoma.