UASt regulatory sequences drive expression of a fusion protein composed of Hsap\EWSR1 amino acids 1-265 fused to sequence that originally encoded Hsap\FLI1 amino acids 242-452, but the Hsap\FLI1 sequence contains a 17 nucleotide deletion that results in the loss of 6 amino acids and a frameshift, thus only amino acids 242-383 of Hsap\FLI1 are present in the fusion protein, followed by a new 64 amino acid sequence.