Anti-U2AF1 antibodies are used in the immunodetection of the protein U2 small nuclear RNA auxiliary factor 1. In humans, the canonical protein has a reported length of 240 amino acid residues and a mass of 27.9 kDa. Its subcellular localization is in the nucleus. Up to 4 different isoforms have been reported for this protein. It is notably widely expressed in many tissue types. A member of the Splicing factor SR protein family, U2AF1 is known to play an important role in both constitutive and enhancer-dependent splicing by mediating protein-protein interactions and protein-RNA interactions required for accurate 3'-splice site selection. The U2AF1 gene has been associated with the disease, Myelodysplastic syndrome. Synonyms for this target antigen include RN, RNU2AF1, U2AF35, U2AFBP, splicing factor U2AF 35 kDa subunit, and FP793. U2AF1 gene orthologs have been reported in the mouse, rat, bovine, frog, chimpanzee and chicken species.