By using recombineering bacterial strain, the transgene with cre/ERT2 was inserted into a bacterial artificial chromosome (BAC: RP23 332E15) containing the mouse Lyve1 promoter and gene. Three strains transmitted the transgene in the germline after crossing with C57BL/6. Line 49 demonstrated the greatest and most reliable tdT induction efficiency and was used in all studies. (J:309509)