The transgene construct consists of the following elements: the human U6 small nuclear RNA 6 promoter driving expression of an sgRNA targeting exon 2 of the the Notch1 gene; a human keratin 14 promoter driving squamous epithelium-specific expression of the cas9 gene; poly(A) signal sequences. In mice carying this allele, the Notch1 gene is knocked out in tissues where the KRT14 promoter is active. Two F0 founder mice were found. Founder 1 has a 74 bp deletion (GATG..TGTC), causing a reading frameshift and premature translation termination. (J:233171)