Southern blot analysis of the murine kininogen gene. Genomic DNA from C57Bl/6J and 129J mice was digested with EcoRV and probed using a 32P-dCTP–labeled PCR product spanning intron 4 and exon 4 of the kininogen gene. This probe hybridized to 2 distinct fragments of genomic DNA, suggesting the presence of 2 kininogen genes.