While EWSR1-FLI1 and SS18-NEDD4 led to distinct gene expression changes, all SSX1-containing fusions clustered together and resulted in a specific upregulation of Polycomb target genes characteristic of a synovial sarcoma gene signature7 (Fig. 3b, c and Supplementary Table 2). Here, NEDD4 is linked to synovial sarcoma.