Igura K, Zhang X, Takahashi K, et al. Isolation and characterization of mesenchymal progenitor cells from chorionic villi of human placenta. Cytotherapy 2004;6:543-53.
This protein causes defects in the differentiation process of human mesenchymal stem cell and neuroectodermal cells, resulting in Ewing sarcoma tumor cells.
Unlike the cells that go on to form, say, your epithelium, which are fixed and neatly arranged in sheets, mesenchymal cells can be situated any-which-way, and can move from place to place.