UASt sequences regulate expression of a Hsap\EWSR1::Hsap\FLI1 fusion protein, with the fusion breakpoints in exon 7 of Hsap\EWSR1 and exon 6 of Hsap\FLI1 (this 'type 1' fusion is found in approximately 60% of Ewing sarcoma patients in which a Hsap\EWSR1::Hsap\FLI1 fusion protein is the causative oncogene).