An FRT-flanked hygro cassette with a 3' loxP site was inserted upstream of exon 3, and an additional loxP site was inserted downstream of exon 7. Flp-mediated recombination removed the hygro cassette and cre-mediated recombination removed exons 3 through 7 floxed. The absence of protein expression was confirmed in liver, muscle, white adipose tissue, brown adipose tissue, kidney, and spleen extracts.