A loxP sequence and phosphoglycerate kinase 1 (Pgk-1) promoter-driven neomycin phosphotransferase (neo) gene flanked by two Flp recognition target (frt) sites was inserted into 493-bp upstream of exon 11, and the second loxP sequence was inserted 243-bp downstream of exon 11. The neo gene was removed in vivo via Flp-mediated recombination in the germline. (J:269480)