A lox66 site was inserted upstream of exon 33. The following vector was inserted into intron 34 (5' through 3'): eGFP, exon 33 splice acceptor site, lox77 site, and FRT flanked neo cassette. Flp mediated recombination removed the neo cassette. Cre mediated recombination inverted the region between lox66 and lox77, bringing eGFP into frame after exon 32. The predicted product is truncated after the 17th calcium-binding epidermal growth factor-like domain (cbEGF17) and called GT8 ("green truncated" from founder mouse 8).