AXL and osteosarcoma: For example, PDGFRα and PDGF‐A correlate with a poor prognosis in OS [17, 18], AXL is frequently overexpressed in OS [19] and promotes osteosarcoma progression by affecting p‐AKT expression [20, 21], and FLT‐3 ligand is significantly associated with poor overall survival and event‐free survival independently of metastasis [22].