A targeting vector was designed to remove parts of exon 2, intron 2, exon 3 and intron 3 of the gene, and also to create a frame shift. The vector contained a floxed cassette containing a neomycin resistance gene and a testes specific angiotensin-converting enzyme promoter driving expression of cre recombinase. The floxed cassette was excised from the locus upon passage through the male germline. (J:117713)