FLI1 and Ewing sarcoma: It, therefore, seems likely that the downstream consequences of the fusion are determined by the aberrant recruitment of a transactivating domain at binding sites determined by the PATZ1 binding domain, perhaps together with upregulated expression via the MN1/EWSR1 promoter, as seen, for example, with EWSR1:FLI1 fusions in Ewing sarcoma [9, 12].