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. Author manuscript; available in PMC: 2009 Feb 7.
Published in final edited form as: Cell Stem Cell. 2008 Feb 7;2(2):151–159. doi: 10.1016/j.stem.2008.01.004

Figure 6. Constitutive expression of the four factors prevents differentiation of iPS cells in teratomas.

Figure 6

Differentiation of iPS cells in teratomas was ablated by continuous expression of transgenes in iPS cells. Tumors derived from iPS cells expressing the four transgenes under the control of the constitutive Ubiquitin C promoter stained homogeneously positive for Oct4 and did not show normal cell differentiation (A). IPS cells harboring the inducible viral backbones differentiated readily after downregulation of the transgenes in the absence of dox (B). The tumors derived from these cells were similar in size, fraction of cells staining positive for Oct4 and differentiation to tumors derived from wildtype control ES cell lines (C) or ES cells harboring the R26-M2rtTA allele (D).