Supplementary Figure 4: Dermal Tomato⁺ cells derived from Lgr5-GFP- and Lgr6-GFP-positive cells are observed in benign squamous tumors.

Lineage tracing of cells derived from Lgr5- and Lgr6-expressing cells 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 3 weeks and 6 weeks thereafter, to measure the extent of lineage tracing from either Lgr5-GFP- or Lgr6-GFP-positive stem cells. (a–d) At 3 and 6 weeks after tamoxifen treatment, Tomato⁺ cells derived from Lgr5-expressing cells (a,c) and Lgr6-expressing cells (b,d) were both observed in the dermal component of papilloma tissue. The yellow dotted boxes demarcate the magnified regions of dermal Tomato⁺ cells in the insets. The white dotted line indicates epithelial–dermal border. The white arrow indicates dermal Tomato⁺ cells. DAPI staining (blue) was performed to localize nuclear staining in sections. The experiment was preformed once using three independent tumors; representative images are provided. Scale bar, 50 μm.