DDX21 and infection: Another study recently showed that knockdown of DDX21 negatively regulates IFN-β production, while overexpression of DDX21 did not affect the production of IFN-β, but promotes the replication of vesicular stomatitis virus (VSV); however, infection with VSV caused the caspase-dependent cleavage of DDX21 and promoted its nucleus-to-cytoplasm translocation to negatively regulate the IFN-β signaling pathway by preventing the assembly of the DDX1-DDX21-DHX36 complex [28].