A transgene consisting of the full human KRT12 gene including introns and containing the Leu132Pro (L132P) mutation in exon 1, an FRT-flanked neomycin resistance gene inserted in intron 2, an F3-flanked puromycin resistance gene inserted into intron 7, a FLAG-HA coding sequence immediately before the termination codon and a multiple targeting cassette (MTC) inserted within the 3'-UTR replaced the mouse Krt12 locus by homologous recombination. The MTC contains about 40 nt including and surrounding the KRT3 mutations c.152G>A (E509K), c.1508G>C (R503P) and C.1493A>T (E498V) and the KRT12 mutations c.395T>C (L132P), c.404G>C (R135T). Flp-mediated recombination excised the selection makers. Western blot analysis confirmed transgene expression. (J:229462)