ASF/SF2, in the presence of elF4E, promotes the initiation of translation of ribosome-bound mRNA by suppressing the activity of 4E-BP and recruiting molecules for further regulation of translation. ASF/SF2 interacts with the nuclear export protein TAP in a regulated manner, controlling the export of mature mRNA from the nucleus. An increase in cellular ASF/SF2 also will increase the efficiency of nonsense-mediated mRNA decay (NMD), favoring NMD that occurs before mRNA release from the nucleus over NMD that occurs after mRNA export from the nucleus to the cytoplasm. This shift in NMD caused by increased ASF/SF2 is accompanied by overall enhancement of the pioneer round of translation, through elF4E-bound mRNA translation and subsequent translationally active ribosomes, increased association of pioneer translation initiation complexes with ASF/SF2, and increased levels of active TAP.