Figure 1.

Targeted disruption of the Mkk3 gene. The structure of the murine Mkk3 gene is illustrated schematically. This gene consists of 12 exons. The coding and noncoding regions of the exons are presented as solid and striped, respectively. The restriction fragments used to construct the targeting vector are indicated (4-kb BglII-BglII fragment and 0.92 kb EcoR5-HincII fragment). The disrupted Mkk3 allele substitutes a Neo^R cassette for exons 8 and 9, which encode the essential protein kinase subdomains VII, VIII, and IX.