An FRT site flanked neomycin resistance gene cassette was inserted into intron 31. A green fluorescent protein (GFP) gene was inserted into exon 31, in-frame after the Thr1366 codon in Divergent Region II. To minimise steric hindrance, the GFP gene was flanked both sides by 10-codon linkers rich in glycine codons. The neo cassette was subsequently removed through flp-mediated recombination. (J:239358)