IGF1 and Ewing sarcoma: Another report revealed that FGFR1 was upregulated in 54.3% of ES patients (Table 1; Agelopoulos et al., 2015), inducing marked EWS-FLI1 upregulation (Girnita et al., 2000a) compared with other ligands, such as insulin-like growth factor-1 (IGF-1), platelet-derived growth factor (PDGF)-BB, hepatocyte growth factor (HGF), epidermal growth factor (EGF), and TGF-β1.