Animals heterozygous for the targeted mutation Smntm1Jme were mated to a cre recombinase transgenic line to delete the floxed exon 7. Deletion of exon 7 in mRNA from the resulting animals was confirmed by RT-PCR analysis. Heterozygous exon 7 deletion animals were intercrossed to generate homozygous mutants. Homozygous mutant embryos were detected by PCR genotype analysis at E9.5. (J:61396)