The exons (Exon 2-4) encompassing the catalytic domain of the gene were replaced with a neomycin resistance cassette. mRNA expression was undetectable in the heart, kidney and liver from homozygous mutant mice. Immunohistochemical staining of epididymis showed the absence of staining in the spermatozoa, luminal space, and luminal cilia on the epithelium in the caput and corpus of the epididymis. (J:161462)