A loxP site was inserted upstream of exon 6. An FRT-flanked neomycin resistance cassette with a 5' loxP site was inserted downstream of exon 9. Flp-mediated recombination removed the selection cassette. Cre-mediated recombination removed exons 6 through 9. This deletion results in a frameshift and premature termination at amino acid 306. Western blot analysis confirmed the absence of protein expression in thymocytes and spleenocytes. (J:232974)