Gene targeting in the mouse is a powerful tool to study mammalian gene func
tion. The possibility to efficiently introduce somatic mutations in a given
gene, at a chosen time and/or in a given cell type will further improve su
ch studies, and will facilitate the generation of animal models for human d
iseases. To create targeted somatic mutations in the epidermis, we establis
hed transgenic mice expressing the bacteriophage P1 Cre recombinase or the
tamoxifen-dependent Cre-ERT2 recombinase under the control of the human ker
atin 14 (K14) promoter. We show that LoxP flanked (floxed) DNA segments wer
e efficiently excised in epidermal keratinocytes of K14-Cre transgenic mice
. Furthermore, Tamoxifen administration to adult K14-Cre-ERT2 mice efficien
tly induced recombination in the basal keratinocytes, whereas no background
recombination was detected in the absence of ligand treatment. These two t
ransgenic lines should be very useful to analyse the functional role of a n
umber of genes expressed in keratinocytes. Copyright (C) 2001 S. Karger AG,
Basel.