A targeting vector was designed to delete exons 19-27. Transcript levels were two- to fourfold lower in mutants than in wild-type animals. RT-PCR confirmed deletion of exons 19-27. A cryptic splice acceptor site in modified intron 27 resulted in an 87-nt 5' extension of exon 28. The resulting protein lacks the GPS, 7TM and C-terminal cytoplasmic sequences. (J:98367)