A targeting construct was designed to insert an internal ribosomal entry site (IRES) and a Cre Recombinase with a polyadenylation signal, followed by a frt-flanked neomycin resistance (neo) cassette, downstream of the stop codon of the corticotropin releasing hormone receptor 2 (Crhr2) gene. The neomycin resistance gene was subsequently removed by crossing with Act-Flpe mice. (J:298576)