This may explain the role of EWS-FLI1 in switching the AS of ARID1A towards the long isoform (Figure 6A) and how, in view of the remodelling activity of BAF, the complex formed by EWS-FLI1, ARID1A-L, and the rest of BAF components activates the transcription of Ewing sarcoma genes in a chromatin-dependent manner. Here, EWSR1 is linked to Ewing sarcoma.