A targeting vector was designed to insert a loxP site upstream of the initiation site of the Epsin 3 (Epn3) gene. A frt-flanked neomycin resistance (neo) cassette, followed by a second loxP site, was placed downstream of exon 9. Cre mediated recombination deleted exons 1 through 9 and the neo. The absence of protein expression was confirmed by immunohistochemistry on parietal cells of the gastric glands. (J:167134)