Consistent with the on-target activity of dBRD9-A, swapping the BRD9 bromodomain for the closely related BRD7 bromodomain (63%, sequence identity) renders BRD9 and synovial sarcoma cells insensitive to dBRD9-A treatment (Figure 5—figure supplement 1A–B and Figure 5—figure supplement 1—source data 1). Here, BRD7 is linked to synovial sarcoma.