A targeting vector was designed to introduce a threonine to asparagine (T1348N) substitution at codon 1348 in exon 29 of the endogeneous locus. In addition, an FRT-flanked neomycin resistance (neo) cassette was introduced approximately 200 bp downstream of exon 29. Flp-mediated recombination removed the FRT-flanked neo cassette. (J:101977)