Cre-mediated excision of the parental Afmidtm1a(EUCOMM)Wtsi allele resulted in the removal of the promoter-driven neomycin selection cassette and the critical exon 2 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. qRT-PCR on liver and kidney confirmed absence of RNA in homozygotes. RNA expression of the immediately adjacent Tk1 gene is reduced by 52% in the kidney and 94% in liver of homozygotes.