DDX21 is a member of the DEAD box family of proteins that possesses several conserved motifs which include the highly conserved DEAD (Asp-Glu-Ala-Asp) amino acid sequence motif. The major activity of DEAD box proteins is to function as ATP-dependent RNA helicases. As helicases, DEAD proteins play an important role in all aspects of RNA metabolism and function which include pre-mRNA splicing, RNA synthesis, RNA degradation, RNA export, RNA translation, RNA secondary structure formation, ribosome biogenesis, and the assembly of RNP complexes. Some members of the DEAD box proteins also exhibit functions involved in transcriptional regulation. DDX21 has been shown to be required for the processing of 20S rRNA to 18S and has also been shown to be important for c-Jun transcriptional activation.