Tryptophan codon 1988 (TGG) in exon 37 was changed to arginine (CGG) (p.W1988R). This mutation is the equivalent of the human p.W1989R mutation found in some bipolar disorder (BD) patients. A loxP site flanked neomycin resistance gene cassette that was inserted into an intron was removed through subsequent Cre-mediated recombination. (J:329513)