The exosome is a multi-protein complex composed of several highly conserved subunits, some of which are 3' to 5' exoribonucleases. The complex is involved in a variety of cellular processes and is responsible for degrading unstable mRNAs that contain AU-rich elements (AREs) in their untranslated 3' regions. DIS3, also known as RRP44, is a 958 amino acid protein that localizes to both the cytoplasm and the nucleus and contains one PINc domain. Widely expressed with highest expression in testis, DIS3 functions as a component of the exosome exoribonuclease complex and is required for processing of 7S pre-RNA into a mature nuclear complex and, ultimately, for proper mitotic progression. Abnormal expression levels of DIS3 may be associated with colon cancer, suggesting a role for DIS3 in tumorigenesis. Multiple isoforms of DIS3 exist due to alternative splicing events.