A loxP site was inserted in exon 1 just in front of the ATG start site and a floxed neo cassette and cDNA containing a mutant form of Lrp5 with a flag tag were inserted in intron 1. The cDNA included 2 mutations 5 glycine and 171 valine. The neo cassette was later removed by Cre mediated recombination. (J:146078)