Required for the export of polyadenylated mRNAs from the nucleus (PubMed:19364924). Enhances ACVR1B-induced SMAD-dependent transcription. Binds to single-stranded DNA but not to double-stranded DNA in vitro. Involved in RNA cleavage (By similarity). Interacts with SMAD1, SMAD3, SMAD4, CPSF2 and CPSF3 (By similarity).