Figure 1.

Disruption of the mkk4 gene in skin epidermis. Adult mkk4^fl/fl mice carrying (+) or not (−) the K14-CreER^T2 transgene were injected intraperitoneally every day for 5 days with a non-toxic amount of tamoxifen (200 μg) to induce Cre activation. The mice were sacrificed 2 weeks later. The epidermises of dorsal skins were separated from dermal tissues. A, Genomic DNA was isolated and amplified by PCR with primers specific for the mkk4 gene. B and C, The specific inactivation of the mkk4 gene in the epidermis of mice expressing Cre was confirmed by immunoblot analyses of protein extracts obtained from various tissues using a specific antibody to MKK4. The detection of tubulin expression was performed to monitor protein loading. Similar results were obtained in two independent experiments.