A targeting vector was designed to introduce a glycine to serine (G2019S) substitution at base pair 107/8 (GG to GC) in exon 41. An FRT-flanked neomycin cassette was introduced into exon 41. LoxP site are also included in the vector although the location is not specified. FLP recombinase mediated recombination removed the neo cassette. (J:230329)