The targeting construct introduced several nucleotide substitutions (N46A [AAT to GCT] and Y50A [TAC to GCC] in exon 2 and N122A [AAC to GCC] and Y126A [TAT to GCT] in exon 3), that results in the amino acid substitutions of alanine for asparagine and tyrosine at positions 122 and 126 (N122A/Y126A). The final allele lacks a self-deleting neomycin resistance cassette. (J:252669)