Exon 1 through 3 were floxed. Cre-mediated recombination removed a floxed neomycin resistance cassette inserted downstream of exon 3. A point mutation results in the amino acid substitution of alanine for arginine at position 114 (R114A). Western blot analysis confirmed an 80%-90% reduction in protein level of this severely hypomorphic allele. (J:204811)