Fig. 1. AdCre1-mediated mammary gland epithelium-specific gene modification. Mammary gland tissue was harvested from all ten glands of late pregnant (14-18 days) animals bearing a floxed allele. Mammary gland tissue was dissociated and enriched for epithelial cells. Those cells were plated on serum/fetuin-coated plastic at a cell density of 
2.5x105/cm2 and cultured for 3 days. Cells were infected with AdCre1 at a MOI 50 and cultured for 2 more days. Cells were injected in epithelium-free fat pads of a 3-week-old host animal on day 5 of culture and allowed to grow out for more than 7 weeks.