Knockout of gankyrin by homologous recombination. ( A) Constructs used to mediate homologous recombination at the gankyrin locus. Exon 1, containing the ATG start codon, was targeted for deletion by homologous recombination using 5’ and 3’ homology arms that were 957 bp and 902 bp in length, respectively. The wild-type allele, targeted allele, and targeted allele after Cre-mediated excision are illustrated. ( B) Confirmation of the knockouts by a PCR screen of genomic DNA. ( C) Southern blot analysis confirmed DNAs were digested with HindIII and AatII and hybridized with the probes depicted in ( D). ( E) Western blot analysis confirmed the protein expression levels of gankyrin. Western blot for tubulin was also carried out to confirm equal loading.