TBC1D9 and sarcoma: Since it was recently shown that, apart from the pathognomonic fusion, also secondary fusions may show oncogenic potential in EWSR1-rearranged sarcomas [52], it would be worthwhile to further investigate the functional role of COPS4-TBC1D9, SMG6-VPS53, and UBE2F-ALS2 in EWSR1-NFATC2-positive patients.