Analysis of two large-scale drug screening data sets (Genomics of Drug Sensitivity in Cancer, Wellcome Sanger Institute, and Massachusetts General Hospital) also identified a highly significant association between the pathognomonic genomic marker in Ewing sarcoma tumors, EWS-FLI, and sensitivity to gemcitabine (Supplementary Fig. S1A and S1B; ref. 26). This evidence concerns the gene EWSR1 and cancer.