In order to ablate phosphatidylinositol 3,4,5-trisphoshate, 3 codons in exon 13 encoding arginine residues 472 through 474 were engineered to instead encoded leucince. A single loxP site remained downstream of exon 14 after a floxed neo cassette used for selection was excised via cre-mediated recombination. (J:90081)