The most common fusion is EWS–FLI1 (Delattre et al., 1992), which encodes an oncogenic transcription factor (May et al., 1993), regulating different target genes (Cidre-Aranaz and Alonso, 2015) governing the initiation and progression of Ewing sarcoma (Riggi et al., 2014). This evidence concerns the gene EWSR1 and Ewing sarcoma.