A construct was generated with a triple-fusion sequence EGFP/cre/PGR (encoding EGFP, cre recombinase, and the human progesterone ligand binding domain - aa F642-L901 of LBD). The fusion gene was cloned downstream of the human lactoferrin promoter (LTF). The LfB-GCrePR1e construct was used for microinjection and 12 founders were obtained. Four founders (#'s 7, 11, 15, and 27) were crossed to R26-lacZ reporter mice. Line 15 was used to generate most of the results in the original study.