その件に関しては論文は以下のように書かれているのよ。
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Despite their similarities, we noted that Fgf4-induced stem cells also possessed some critical differences compared with blastocyst-derived trophoblast stem cells. First, Fgf4-induced stem cells exhibited moderate GFP signals and expressed a moderate level of Oct4 (Fig. 2b; moderate and low levels of immunostaining signals were also seen for Oct4 and Nanog proteins, respectively; Extended Data Fig. 2c), unlike conventional trophoblast stem cells that have little Oct4 expression (Fig. 2e). Second, unlike trophoblast stem cells, blastocyst-injected Fgf4-induced stem cells also contributed to embryonic tissues (in all cases that involved chimaeric placentae; n = 32), although the extent of contribution was generally modest (Fig. 2g).
論文上の理由ははっきり書かれてはいるのね。
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However, as Fgf4-induced stem cells lay between STAP stem cells and trophoblast stem cells in the dendrogram, the possibility of contamination of STAP stem cells in the Fgf4-induced stem-cell population cannot be ruled out.
先にe,fのリジェンドを見て置いたら?
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e, f, For an additional control, Fgf4-induced stem cells were plated in trophoblast stem-cell medium containing Fgf4 together with Oct4-GFP ES cells that constitutively expressed BFP (the number of plated cells was one-tenth of that of plated Fgf4-induced stem cells). Whereas BFP-expressing colonies (ES-cell-derived) still expressed Oct4-GFP in trophoblast stem-cell culture medium after 2 days (e), no Oct4-GFP+ colonies from BFP-expressing ES cells were observed in the JAK-inhibitor-treated culture (f).
<BFP-transfected Oct4-GFP ES cells>の説明があるね。
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Oct4-GFP ES cells that constitutively expressed BFP (the number of plated cells was one-tenth of that of plated Fgf4-induced stem cells)
