Figure 2. Cre targeting in large intestinal stem cells.

p53^lox/lox × Lgr5^CreERT2 mice were injected with tamoxifen (f/f Cre TX) (1 mg/day) for 5 consecutive days. Control p53^lox/lox × Lgr5^CreERT2 mice were not injected with tamoxifen (f/f Cre). A. Representative image of Cre+ cells (white) colocalized with GFP+ stem cells (green) and nuclei (blue). Following tamoxifen injection, inducible Cre recombinase fused to a mutant estrogen ligand-binding domain was able to enter the nucleus, where it excised the “floxed” cassette. Therefore, only the nuclear localized Cre is considered “activated” for recombination purposes. B. Percentage of GFP+ stem cells that are positive for nuclear Cre (mean ± SE, from 3 mice).