A three base deletion of TTC at nucleotide positions 1130-1132 in exon 9 was created. This causes the deletion of phenylalanine at amino acid residue 377. At the same time, a floxed PGK neomycin selection cassette was inserted in intron 8 608 bp 5' of the TTC deletion. Founder mice were crossed to cre expressing mice in order to excise the selection cassette. (J:168526)