SENP1 and metastasis: However, the plasma exosome-derived SENP1 levels of patients with osteosarcoma with tumor size >10 cm, located in the distal extremity, necrosis rate >90%, pulmonary metastasis, and surgical stage III; +IV were significantly higher than in patients in with tumor size <10 cm, located in the proximal extremity, necrosis rate <90%, without pulmonary metastasis, and in surgical stage ι+II (P < 0.05, Figures 3C–G).