Fig 1: nMRTF BCC chromatin accessibility resembles hair follicle matrix.a IF representative images of MRTF cellular localization in healthy mouse skin, in comparison to localization of HHIP (Hh-responsive matrix transit-amplifying cells), Keratin-14 (interfollicular epidermis and outer root sheath), and phospho-Smad2/3 (TGFß-responsive dermal papilla and matrix transit-amplifying cells). Inset areas (IFE top row, HF matrix bottom row) denoted by white dotted boxes. Single-color images are all derived from the same slide except for pSmad2/3, due to limitations of antibody co-staining. Images are representative of n > 50 hair follicles examined. Scale bar at low power = 50 µm, inset = 25 µm. b IF images of MRTF localization in clinical biopsies of basal cell carcinoma with nuclear or cytoplasmic MRTF (BCC-nMRTF or -cMRTF), pilomatricomas (PMX), epithelial inclusion cysts (EIC), and pilar cysts (PC). Images are representative of n = 3 patient tumors per subtype. Scale bar = 50 µm. c Principal component analysis (PCA) plot showing the relationship of ATAC-seq profiles between resistant BCC cell line ASZ001 (res-BCC), sensitive murine BCC (sens-BCC), basal transit-amplifying cells of hair follicle (basal TAC), bulge hair follicle stem cells (Bulge), hair germ (HG), interfollicular epidermal stem cells (IFE), and suprabasal transit-amplifying cells of the hair follicle (suprabasal TAC). See Supplementary Table 1 for data sources. d IF images of MRTF, Ki67, and Krt14 in mouse hair follicle skin explants treated with DMSO vehicle or 150 µM MRTFi CCG-1423 for 72 h. Scale bar = 20 µm. e Quantification of Ki67+ cells per hair follicle in (d). n = 4 pairs of explants from three mice. ***p < 0.0001. f Representative H&E staining of DMSO or CCG-1423 treated mouse skin explants. Scale bar = 100 µm. g Quantification of hair follicle lengths in (f). Each point represents the length of one HF averaged over up to three separate measurements. **p = 0.0017. All error bars represent mean +/- SD. p-values were calculated using unpaired, two-tailed Student’s t-test.