Cre-mediated excision of the parental Cul5tm1(KOMP)Vlcg allele resulted in the removal of the neomycin selection cassette and critical exon 2 through 6 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.