EWSR1 and Ewing sarcoma: The FET (FUS, EWSR1, and TAF15) fusion oncogenes are characteristic for around 20 different sarcomas and leukemia, including FUS::DDIT3 in myxoid liposarcoma (MLS) and EWSR1::FLI1 in Ewing sarcoma (EWS), the two most common FET sarcoma entities (Fig. 1A).