A. The three normal RNA-binding FET proteins consist of N-terminal repetitive and structurally disordered domains (NTD: N-terminal domain), central RNA-binding domains (RRM: RNA recognition motifs), zinc finger domains (ZF) and degenerated repeat regions (RGG: RGG repeat regions). The GST-tagged FET-NTD baits shown were used for pulldown experiments and represent the shortest parts commonly present in the FET fusion oncoproteins. The FET binding motif is a conserved sequence required for complex formation between the three FET proteins. Amino acid numbers are indicated. 