EWSR1 and Ewing sarcoma: GLI1 is a direct transcriptional target of EWSR1-FLI1 oncoprotein which is a fusion transcript found in Ewing sarcoma family of tumors and consists of EWSR1 (RNA binding protein 1) and FLI1 (Fli-1 proto-oncogene, ETS transcription factor) genes [138].