Using BAC RP23-314P12, exon 6 was targeted for a mutation changing serine codon 89 to a glycin codon (p.S89G) and an FRT site flanked neomycin resistance gene cassette was inserted into intron 6. The neo cassette was removed through subsequent flp-meditaed recombination. This mutation prevents the glycosylation of the residue in the encoded peptide. (J:278186)