Fig. 2

C-Kit-CreER targeted McSCs form epidermal melanoma following induction of Braf:Pten mutations. a Schematic shows TAM treatment and analysis regimen of b–h. b Immunofluorescence images show Dct (red) and pAKT (green) in control (left) and c-Kit-CreER:Braf:Pten (middle) skin at 7 days after initial TAM. Dot plot shows percentage of pAKT⁺ cells in Dct⁺ McSCs (right) (mean ± s.d.; n = 30 hair follicles from 3 control mice in control and 33 hair follicles from 3 c-Kit-CreER:Braf:Pten mice). c Immunofluorescence images show Dct (red) and Ki67 (green) in control (left) and c-Kit-CreER:Braf:Pten (middle) skin at 7 days after initial TAM. Dot plot shows percentage of Ki67⁺ cells in Dct⁺ McSCs (right) (mean ± s.d.; n = 30 hair follicles from 3 control mice in control and 36 hair follicles from 3 c-Kit-CreER:Braf:Pten mice). d Immunofluorescence images showing GFP (green) in c-Kit-CreER; R26R-GFP control mice (left panel) and GFP (green) and Dct (red) in c-Kit-CreER:Braf:Pten:GFP mice (right panels) at 10 days after initial TAM (Left). The rightmost panels show the separate channel images to demonstrate the co-localization of GFP and Dct signals. e Dot plot shows percentage of 6um tissue sections ( > 500  µm length) that contain Dct⁺/GFP⁺ epidermal melanocytes in control and c-Kit-CreER:Braf:Pten:GFP mice (mean ± s.d.; n = 3 mice, total number of tissue sections analyzed is indicated in parenthesis in each group). f Schematic model showing that upon oncogenic mutations, McSCs expand in the niche and migrate upward to the epidermis. g Immunofluorescence images showing GFP (green) and Dct, S100b, Sox10, MITF (red), H&E or brightfield images in c-Kit-CreER:Braf:Pten:GFP mice at 21 days after initial TAM. h Immunofluorescence images showing Tomato (red) and Dct, S100b, Sox10, MITF (green), H&E or brightfield images in Tyr-CreER:Braf:Pten:Tomato mice at 21 days after initial TAM. Dashed line outlines the boundary of epithelium and dermis. Scale bars, 25 μm, except for d and the leftmost panel of g and h, which are 50 μm. Arrowheads point to follicular McSCs, except in d, where they also define epidermal melanocytes. HF hair follicle, McSCs melanocyte stem cells, SG sebaceous gland, DP dermal papilla. Source data are provided as a Source Data file