Flp recombinase expression was used to excise an FRT flanked neo cassette. Subsequent expression of cre removed the loxP flanked exons 8 and 9. Real time PCR analysis confirmed loss of exon 8 and 9 expression in homozygous mutant mice. The mutant RNA transcript codes for a truncated translation product that lacks the C-terminal 219 amino acids, because deletion of exons 8 and 9 results in a frameshift mutation and introduces a premature stop codon 40 bp downstream of the start of exon 10. Western blot analysis of membrane protein extracts from mutant neutrophils using an antibody that reacts with amino acids 353-370 confirmed loss of expression of this critical C-terminal region.