In (G4C2)n-polyA models (top panel), repeat RNA is transported to the cytoplasm, where it is translated into DPR proteins. Diffuse G4C2 RNA is detected mostly in the cytoplasm, and higher toxicity correlate with high levels of DPR protein production. In intronic (G4C2)n models (bottom panel), repeat RNA accumulates in the nucleus as RNA foci and less DPR protein is produced. Thus, only low levels of toxicity are observed.