Mice were selected by PCR of mouse-tail DNA with specific primers as described below. Indicated are the sequences and the approximate length of the amplified DNA fragments. TgCre4: rspCre1 (5′- ACCAGGTTCGTTCACTCATGG-3′) and rspCre2 (5′- AGGCTAAGTGCCTTCTCTACAC-3′), 200 basepairs (bp).