An FRT flanked neo cassette and a loxP site were inserted in intron 5. A second loxP site was inserted in intron 6. Exon 6 which encodes part of theFERM domain is thus flanked by loxP sites. Deletion of exon 6 by cre mediated excision also results in a frame shift creating a stop codon in exon 7. Both 145 and 125 kDa protein isoforms were lost as determined by immunoblotting.