Fig. 3: The maintenance of adult CD34⁺ HF bulge stem cells is dependent on MCL‑1.

A, B Deletion of Mcl‑1 resulted in the gradual reduction of the CD34⁺ HF bulge cell subset. Representative FACS plots for skin epithelial cells fractionated based on CD34 and SCA‑1 expression from K5‑Cre/Mcl‑1^f/f mice or littermate control mice at p21, p60 and p90 (n = 4) (A). Bar graphs showing the percentages of the indicated cell sub‑populations within the CD49f⁺ epithelium isolated from the dorsal skin of K5‑Cre/Mcl‑1^f/f, K5‑Cre/Mcl‑1^f+, Mcl‑1^f/f or Mcl‑1^f/+ mice at p21, p60 and p90. Data are presented as mean ± SEM (n = 4 mice for each genotype). *p < 0.05; **p < 0.01; ***p < 0.001; n.s., non‑significant; Student’s t‑test (B). C Western blot analysis of the indicated BCL‑2 family members in the CD49f^– (non‑epithelial cells), CD49f⁺/SCA‑1^– (HFs), CD49f⁺/SCA‑1⁺ IFE populations of HFs at telogen (p60). Data shown are representative of n = 4 independent experiments. D Representative confocal images showing the expression of MCL‑1 and BIM protein in HF stem cells marked by CD34⁺ and KRT15⁺ in hair bulges at telogen phase (p60). Representative of n = 3 experiments. Scale bar, 50 µm. Hair matrix containing TACs is stained by PCAD, and DAPI is used as a nuclear counterstain in each image. E In vitro clonogenic assay of the CD34⁺ HF bulge stem cells. 100 Lin^–/CD49f⁺/CD34⁺/SCA‑1^– cellsisolated from the skin of K5‑Cre/Mcl‑1^f/f mice and littermate control mice at p21 were grown on 3T3 feeder cells for 14 days. Bar graphs show the numbers of colony‑forming cells among the seeded CD34⁺ HF bulge cells. Data are presented as mean ± SEM for n = 3 independent experiments. **p < 0.01; Student’s t‑test.