A loxP site and an FRT-flanked PGK-neomycin cassette (in reverse transcriptional orientation) are placed in intron 3 along with a loxP site in intron 7 (thus flanking exons 4-7 with loxP sites). In addition, an Arg215His (R215H amino acid; G644A nucleotide) mutation is introduced to exon 4 of the gene. Flp-mediated recombination removed the FRT-flanked neo cassette. The Arg215His (R215H) loss-of-function point mutation in the human gene has been identified in schizophrenia patients. (J:101977, J:272181)