Extended Data Figure 3: UVR induces naevogenesis in BRAF(V600E) mice.

a, Schematic representation of experimental processing of mouse skin. Three skin sections (long rectangular boxes) were cut perpendicular to the longitudinal axis of the mice to span the UVR-exposed and protected areas (as marked by the dotted line) of the tamoxifen-treated shaved area (pink). b, Photomicrograph of H&E-stained representative skin from the protected and UVR-exposed skin of a tamoxifen-treated BRAF(V600E) mouse subjected to UVR exposure and examined at 7 days (n = 5). Dotted line: UVR treatment line demarcation. Scale bar, 0.4 mm. c, Photomicrograph of H&E-stained skin from the boxed black area in b, showing the cloth-protected skin of a tamoxifen-treated BRAF(V600E) mouse subjected to UVR exposure and examined at 7 days. Black boxes show individual naevi. Double-headed arrow shows example of maximum diameter of a single naevus. Scale bar, 300 µm. d, Photomicrograph of H&E-stained skin from the dashed boxed black area in b, showing the UVR-exposed skin of a tamoxifen-treated BRAF(V600E) mouse subjected to UVR exposure and examined at 7 days. Black boxes show individual naevi. Scale bar, 300 µm. e, Photomicrograph of H&E-stained skin from the cloth-protected and UVR-exposed skin of a tamoxifen-treated CreERT2 control mouse subjected to weekly UVR exposure for 6 months. Scale bar, 300 µm. f, Photograph showing macroscopic appearance of protected and UVR-exposed skin from the tamoxifen-treated CreERT2 control mouse shown in a. Original magnification, ×2.