An FRT flanked construct containing splice acceptor site, beta-gal, neo and polyA sequences and loxP site were inserted upstream of exon 3 and a loxP site was inserted downstream of exon 3 via homologous recombination. The targeting vector (design ID 39122) was obtained from the EUCOMM repository. Flp mediated recombination removed the beta-gal, neo construct. (J:219976)