Figure 1.

Creation of mutant mice. (a) Mice were bred and genotyped using PCR. The presence of the IR mutant allele results in a 240-bp product, while there is no product in the wild-type (WT) allele. The presence of the wild-type allele for the IRS-1 gene results in a 440-bp product; insertion of the neomycin cassette in the targeted allele results in a band of 1.25 kb. In the case of the Pik3r1 gene, the mutant allele results in a band at 600 bp, whereas the wild-type allele yields a 750-bp product. (b) Body weight of the various subgroups of mice was determined at the indicated ages. Results are expressed as mean ± SEM (n = 12–30 mice per genotype).