Overall, our genome-wide characterization of GGAA-microsatellites identifies two distinct classes of EWS/FLI-bound GGAA-microsatellites, demonstrating the integral relationship of microsatellite length and gene proximity to facilitate EWS/FLI binding and transcriptional activity in Ewing sarcoma (Fig 5). Here, EWSR1 is linked to Ewing sarcoma.