Cre-mediated excision of the parental Dis3tm1e(EUCOMM)Hmgu allele resulted in the removal of the promoter-driven neomycin selection cassette 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.