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. Author manuscript; available in PMC: 2014 Apr 15.
Published in final edited form as: Nature. 2009 Aug 9;460(7259):1145–1148. doi: 10.1038/nature08285

Figure 1. Reprogramming efficiency of fibroblasts is influenced by replicative potential and ARF expression status.

Figure 1

(a) Alkaline phosphatase (AP) staining (top) of iPS cell colonies derived from secondary murine embryonic fibroblasts (MEFs) at different passages (P). Senescence associated β-galactosidase activity (bottom) of MEFs at same passages. (b) Expression levels of p16INK4a, ARF and p21Cip1 in MEFs at the same passages as shown in (a). (c) Western blot analysis for p16INK4a and phospho-p53 (p53*) in MEFs grown at low (4%) or high (21 %) oxygen. (d, e) Secondary MEFs grown under low O2 give rise to iPS cells more efficiently. (f) ARF-GFP reporter MEFs (green line) at passage 3 show heterogeneous expression levels. Shown in red are wild type (WT) MEFs. (g, h) ARF-GFPlow MEFs give rise to transgene-independent AP+ iPS colonies more efficiently than ARF-GFPhigh cells. Error bars depict the s.e.m.