Cre-mediated excision of the parental Cfap69tm1a(KOMP)Wtsi allele resulted in the removal of the promoter-driven neomycin selection cassette and critical exon 5 leaving behind the inserted lacZ reporter sequence. Further information on targeting strategies used for this and other IKMC alleles can be found at http://www.informatics.jax.org/mgihome/nomen/IKMC_schematics.shtml. Western blotting analysis of whole testis lysates confirmed the absence of protein expression in homozygous mutant males.