もうひとつ上記記載で興味深いのは、[および、ES 細胞 129/GFP ES は]の部分である。129/GFP ES は持ち主不明の細胞であり、これがES細胞かどうかは不明とされている。それをあえて公式報告書において、ES細胞と決めつけた。このES細胞との言葉を入れた書き方は、読者が疑問を持つように、わざわざと誘っている感がある。
BCA論文 Furthermore, these STAP cell lines shared two genomic characteristics with FES1, but not FES2; first, two chromosomal deletions (Fig. 1a) are present only in FES1 and all Acr/cag-GFP STAP stem-cell sublines, but not in the other cell lines examined, in the paternal Acr/cag-GFP mice (frozen stock in 2010), or in potential maternal 129 substrains available in Japan. Second, FES1 and the STAP cell lines with Acr/cag-GFP share large SNP clusters that differ between FES1 and FES2 in three chromosomes (Fig. 1b and Extended Data Fig. 1b, c).
＞These differential SNP clusters probably arose from chromosomal heterogeneity in the parental mouse colonies when FES1 and FES2 were established. It is highly unlikely that the Acr/cag-GFP STAP cell lines and FES1 all independently acquired these two unique deletions and inherited the same three mosaic chromosomes from parental mice.
After the above three SNP clusters reflecting parental heterogeneity are excluded, the remaining 1,290 SNP alleles that distinguish FES1 and FES2 are supposed to have accumulated at or after establishment in 2005. Regarding these SNPs, STAP cell lines FLS3 and CTS1 and 129/GFPES cells are nearly identical, but differ slightly from FES1 (at 30% of these alleles), suggesting that STAP cell lines FLS and CTS were derived from a sub-stock of FES1 ES cells.