LoxP sites were inserted 5' and 3' of the keratin type I gene cluster. Cre mediated recombination deleted the entire cluster leaving a single loxP site from Krt222 to Krt17. The absence of the transcripts and gene products was confirmed by RT-PCR and immunofluorescence microscopy in homozygous embryos. ES cells carrying Krt31ctm1Tmm and Krt31ctm2Tmm and were used to create this deletion. (J:230728)