cDNA encoding cre/ERT was inserted at the initiation codon of Fstl4 in a BAC containing 128 kb of murine Fstl4, replacing the translational start site of the gene. The cre/ERT sequence was followed by an frt-flanked neo cassette and a polyadenylation signal. The neo was removed from the germline by crossing to a mouse strain expressing Flp recombinase. (J:157687)