A cassette containing a splice acceptor, the open reading frame of Sh3gl1, an IRES-EGFP and an FRT-flanked neomycin resistance cassette was flanked by inward facing loxP sites and inserted in opposite orientation between exon 8 and 9. Flp-mediated recombination removed the selection cassette. Cre-mediated inversion is required to achieve expression of the fusion at exon 8. The fusion products mimick a fusion found in human patients with leukemia. (J:205605)