mRNA export is a process that is tightly coupled to mRNA splicing (1-4). Splicing of mRNAs and the packaging of mRNAs in the form of mRNA-protein complex (mRNP) leads to the recruitment of the mRNA export adaptor THOC4/ALY via its interaction with the splicing factor UAP56, forming a large complex termed transcription-export complex (TREX) (1,2,5). THOC4/ALY then directly interacts with NXF1/TAP, a part of the heterodimer that targets the mRNP to the nuclear pore complex, resulting in the shuttling of mRNP out of the nucleus to the cytoplasm (1-3,6).