To determine whether SLFN11 directly affected the cytotoxic property of TAS1553, we examined the effect of SLFN11 knockdown using siRNA on the cytotoxicity of TAS1553 in an Ewing sarcoma cell line A673 (which had the highest SLFN11 expression among the 22 cell lines). The gene discussed is SLFN11; the disease is Ewing sarcoma.