Nonetheless there is increasing evidence that MSCs are able to serve as progenitor cells for certain, mainly soft tissue, tumors: The experimental silencing of the Ewing sarcoma specific EWS-FLI1 fusion transcript could partially restore the adipogenic differentiation potential of an ES tumor cell line, a property which the tumor cells do not display under native conditions. This evidence concerns the gene FLI1 and Ewing sarcoma.