Figure 3

Phenotype of ABCG2-positive keratinocytes. (A) Expression of stem cell markers in human epidermal keratinocytes. ABCG2-positive and ABCG2-negative keratinocytes were sorted separately as in Figure 2. ABCG2-positive cells (blue line) were more strongly stained with antibodies to α6-integrin, β1-integrin, keratin 14 and p63 than ABCG2-negative cells (green line); CD71 and involucrin staining was weak in ABCG2-positive cells; both ABCG2-positive and ABCG2-negative cells were unstained for CD34 and C-kit. Isotype control, red line. (B, C) Colonies formed by ABCG2-positive keratinocytes and ABCG2-negative keratinocytes. ABCG2-positive and ABCG2-negative keratinocytes were sorted and seeded onto a lethally irradiated 3T3 feeder layer, and allowed to grow for 7 days. (B) ABCG2-positive keratinocytes formed a large colony, composed of small and actively growing keratinocytes. (C) ABCG2-negative keratinocytes formed small colonies, with irregular margin and big keratinocytes, indicating an abortive colony. Scale bars: B, C, 100 μm.