Anti-DDX21 antibodies are used in the immunodetection of the protein DExD-box helicase 21. In humans, the canonical protein has a reported length of 783 amino acid residues and a mass of 87.3 kDa. Its subcellular localization is in the nucleus, mitochondria, and cytoplasm. Up to 2 different isoforms have been reported for this protein. It is notably widely expressed in many tissue types. A member of the DEAD box helicase protein family, DDX21 is reported to be a RNA helicase that acts as a sensor of the transcriptional status of both RNA polymerase (Pol) I and II: promotes ribosomal RNA (rRNA) processing and transcription from polymerase II (Pol II). Synonyms for this target antigen include GURDB, II/Gu, RH, RH II/Gu, RH-II/GU, RH-II/GuA, gu-alpha, and GUA. DDX21 gene orthologs have been reported in the mouse, rat, bovine, frog, zebrafish and chimpanzee species. Over 50 citations in the literature describe the use of DDX21 antibodies in research. Western Blot is a widely used application for these antibodies. Immunocytochemistry, Immunofluorescence, and Immunohistochemistry are also common applications.