Supplementary Figure 3: LGR reporter–Tomato lineage-tracing treatment regime and sample collection.

(a,b) Lineage tracing using Tomato expression driven from Lgr5 (a) and Lgr6 (b) was performed in chemically induced skin tumors from Lgr6-EGFP-CreERT2 and Lgr5-EGFP-CreERT2 mice crossed with Rosa26-LSL-Tomato reporter mice by standard DMBA treatment followed by 8 weeks of tumor promotion using TPA. Mice were then treated with tamoxifen (TAM), and papillomas were harvested at 2 d, 3 weeks and 6 weeks thereafter, to measure the extent of lineage tracing from either Lgr5-GFP- or Lgr6-GFP-positive stem cells.