A flippase recombinase target (FRT)-flanked region containing the LacZ beta-Galactosidase and Neomycin expression genes and a LoxP-flanked region containing exons 4 and 5 was inserted into the gene. The LacZ beta-Galactosidase and Neomycin cassettes were removed via Flp-mediated recombination in the germline, leaving loxP sites flanking exons 4 and 5. (J:240623)