达能促进胚外内胚层，而SOX17则诱导定型内胚层。）
胚胎干细胞是一种具有独特生物学特性的细胞，它能进行自我更新，并且能分化为内胚层、中胚层和外胚层细胞。因此，了解胚胎干细胞和相关分化细胞的细胞命运调控过程及影响因素，将帮助我们更好地研究胚胎发育，并将有助于治疗各种疾病。
在2008年8月7日出版的《细胞—干细胞》（Cell Stem Cell）杂志上，来自加拿大的一组科学家发表了他们关于细胞命运调控的最新研究结果。研究小组通过派系决定（lineage-determining）转录因子的表达研究了内胚层细胞的命运调控。结果证实，通过SOX7或者SOX17的组成性表达（constitutive expression），人类胚胎干细胞能形成稳定的内胚层祖细胞。组成性表达是一类不大受到环境变动而变化的基因表达，SOX7和SOX17的这种表达过程能分别产生胚外内胚层和定型内胚层祖细胞。
研究中科学家们还发现，在畸胎瘤（teratoma）分析和生长因子调节的分化过程中，SOX7似乎被局限于胚外内胚层中，而与此同时，SOX17细胞则在畸胎瘤中表现出一种中内胚层显性，并且显示出在缺少细胞因子调节的内胚层诱导情况下发生内胚层成熟的能力。
科学家最后表示，新发现提供了一种研究内胚层分化过程的新工具。（生物谷Bioon.com）
生物谷推荐原始出处：
Cell Stem Cell，Vol 3, 182-195, 07 August 2008，Cheryle A. Séguin, Janet Rossant
Establishment of Endoderm Progenitors by SOX Transcription Factor Expression in Human Embryonic Stem Cells
Cheryle A. Séguin,1, Jonathan S. Draper,1,2,4 Andras Nagy,2,3 and Janet Rossant1,3,
1 The Hospital for Sick Children, Program in Developmental and Stem Cell Biology, Toronto, ON M5G 1L7, Canada
2 Samuel Lunenfeld Research Institute, Mount Sinai Hospital, Toronto, ON M5G 1X5, Canada
3 Department of Molecular Genetics, University of Toronto, 1 King's College Circle, Toronto, ON M5S 1A8, Canada
In this study, we explore endoderm cell fate regulation through the expression of lineage-determining transcription factors. We demonstrate that stable endoderm progenitors can be established from human ES cells by constitutive expression of SOX7 or SOX17, producing extraembryonic endoderm and definitive endoderm progenitors, respectively. In teratoma assays and growth factor-mediated differentiation, SOX7 cells appear restricted to the extraembryonic endoderm, and SOX17 cells demonstrate a mesendodermal phenotype in teratomas and the ability to undergo endoderm maturation in vitro in the absence of cytokine-mediated endoderm induction. These endoderm progenitor cells maintain a stable phenotype through many passages in culture, thereby providing new tools to explore the pathways of endoderm differentiation.
