Targeting vector PG00105_W_3_A10 from the IKMC was used to generate the allele. An frt-lacZ-loxP-neo cassette-frt-loxP construct was inserted into intron 3 and a single loxP site was inserted into intron 4. Cre-mediated recombination of the loxP sites resulted in the removal of the neo cassette and exon 4 from the germline. No expression was detected in the sperm, trachea or ependyma of homozygous mutant mice at the mRNA or protein level. (J:278278)