This allele was generated by breeding mice heterozygous for Ramp1tm1Tsuj with transgenic mice ubiquitously expressing cre recombinase. Exon 2 of the gene and the neomycin resistance cassette were removed, leaving behind a single loxP site. Upon deletion of exon 2, the splicing of exons 1 to 3 created a frameshift that resulted in the introduction of a termination codon at the beginning of exon 3. RT-PCR analysis of the thymus indicated there was no transcription of the wild-type gene. (J:125974)