DDX3 contains all of the motifs of the DEAD-box family of RNA helicases, including the Asp-Glu-Ala-Asp sequence that gives the protein family its name and distinguishes it from other RNA helicases. DDX3 is localized to the X chromosome and has a highly conserved functional homolog (DBY) on the Y chromosome. DDX3 is thought to be involved in RNA splicing, RNA transport, and translation initiation. It has also been shown to be involved in cell growth control and is deregulated in hepatitis virus-associated hepatocellular carcinoma. Recent experiments suppressing DDX3 expression blocked HIV-1 RNA export from the nucleus, suggesting that DDX3 functions as a shuttling protein that transports the HIV-1 protein Rev and its cofactor CRM1 from the nucleus to the cytoplasm.