The targeting construct introduced into the locus an FRT-flanked neomycin resistance cassette, eight tandem repeats of the Lef/Tcf binding site (CCTTTGATC), a minumal heat shock 68 promoter, floxed stop cassette, a histone H2B-GFP-6xMyc fusion protein and bovine growth hormonr 3'UTR. (J:256044)