EDN1 and Ewing sarcoma: As such, the ability of XI-006 to enhance the cytotoxic effects of four standard Ewing sarcoma chemotherapeutic agents (vincristine, actinomycin D, doxorubicin or etoposide) was assessed in five Ewing sarcoma cell lines (TC252, STA-ET-1, WE-68, RD-ES, and SK-N-MC).