An H662A (histidine to alanine; CAT to GCT) mutation was introduced to a catalytic site encoded by exon 14 via a recombineering strategy. A loxP-flanked neomycin resistance selection cassette was placed upstream, in intron 13. Germ line, cre-mediated recombination removed the neomycin cassette. Please note that an error in the publication indicates that the mutation was introduced into exon 12, the correct exon is 14. (J:101977, J:204353)