Fig. 2. Runx1 expression in HF during SC activation. (A) FACS of skin cells after 4 weeks of H2B-GFP repression shows GFP epifluorescence, and surface CD34 and 6-integrin expression. (B) RT-PCR for Runx1b in the HFSC pool (CD34+/6+/GFP^high) relative to other epithelial skin cells (CD34-/6+/GFP+). (C) Skin at second telogen-anagen transition (a) from mice in A. Skin at first telogen-anagen transition (PD21) from Runx1^lacZ/+ (b) and wild-type (c-e) mice. Staining for Runx1 and Ki67 (d,e) show HFs from serial sections. Arrows (c,d) indicate bulge CD34+/nuclear Runx1+ cell, enlarged in inset. Arrow in e points to a Ki67+ bulge cell, which is indicative of early stage of stem/progenitor cell proliferation (activation). Ep, epidermis; Bu, bulge; hg, hair germ, DP, dermal papillae. Scale bars: 20 µm. Blue is DNA DAPI staining.