Normal DMPK Transcript Mutant DMPK Transcript 三三 (CUG)n expansion pre-mRNP△(CUG)5—3 EXP protein RNA EXP protein processing recruitment RNA processing 5- 3 nuclear EXP binding site mutant mRNP EXP/DMPK RNA foci normal 5 3 mRNP (A)n export export blocked NPC NUCLEUS EXP CYTOPLASM recruitment 5 3 cytoplasmic EXP binding site