A loxP-flanked transcriptional stop signal in the antisense direction was inserted into intron 6. Exon 7 was fused to exons 5-9 of human FLI1 with a C-terminal FLAG tag, and a 3' neo cassette, replacing exons 8 through 11 by homologous recombination. The absence of endogenous protein product was confirmed by western blot analysis. (J:156860)