A loxP site followed by a cDNA containing exons 20 - 22 and the 3' UTR replaced exons 20 - 22 resulting in the removal of introns 20 and 21. This was followed by an FRT flanked neo cassette. In addition a second loxP site followed by a 335 bp of intron 19 and a short exon 20 - 22 cDNA with mutations in exon 20 and 22 that disrupt the lipid binding domain in the tail of the protein were inserted behind the first construct. Flp mediated recombination removed the neo cassette. RT-PCR analysis detected both the full length transcript and a splice variant skipping exons 19 and 20. The reading frame was intact in this variant and immunoblot analysis detected the presence of a mutant protein lacking 68 amino acids.