A targeting vector was designed to insert a frt-flanked neomycin resistance (neo) cassette followed by a loxP site upstream of exon 3, and a second loxP site downstream of exon 12 of the adenylate cyclase 6 (Adcy6) gene. Flp-mediated recombination removed the neo cassette and left exons 3 through 12 floxed. (J:180012)