In summary, we have identified a soluble peptide comprising of amino acids from the fusion region of EWS-FLI1 gene which can inhibit the tumorigenic properties of Ewing’s sarcoma cells in-vitro, and interact with EWS-FLI1, EWS-FLI1- DNA complex and with proteins present in EWS-FLI1 complexes. Here, FLI1 is linked to Ewing sarcoma.