SOX9 and osteosarcoma: Using Kaplan–Meier method and log-rank test, the overall survival (OS, Figure 2A, P < 0.001) and disease-free survival (DFS, Figure 2B, P < 0.001) of osteosarcoma tissues with high SOX9 expression were both significantly shorter than those with low SOX9 expression (both P < 0.001).