Figure 2.

Generation and analysis of transgenic mice expressing the CreER^tam fusion protein in skin epithelia. (A) Schematic representation of the transgene. (B) PCR analysis of the DNA extracted from different organs of K14–CreER^tam/Cre–MATE double-positive animals before and after oral administration of tamoxifen. PCR was conducted as described in the legend for Fig. 1. (C) Immunohistochemical assay for Cre activity in transgenic mouse skin. Double-positive K14–CreER^tam/ROSA26 Cre test or single-positive ROSA26 Cre test transgenic mice were used in this experiment. Tamoxifen in DMSO or DMSO alone was applied to the skin once a day for 5 days. A day after the last application, skin biopsies were taken and sections were stained for β-galactosidase activity. Shown are the results from ROSA26 Cre test mouse treated with tamoxifen (Left); double-positive ROSA26 Cre test/K14–CreER^tam mice treated with DMSO (Center); and double-positive mice treated with tamoxifen (Right). Triangles, loxP sequences; the arrow denotes a single cell positive for β-galactosidase in the skin from double-positive ROSA26 Cre test/ K14–CreER^tam mouse treated with DMSO. (Bar = 50 μm.)