Investigating nucleo-cytoplasmic shuttling of the human DEAD-box helicase DDX3.

•Human DDX3 protein requires its N-terminal NES for nuclear export and CRM-1 binding.•DDX3 contains at least three independent nuclear localisation signals.•DDX3’s subcellular localisation is relatively refractory to viral infection, cytokine stimulation and DNA damage.•DDX3 accumulates in the nucleus during prophase/pro-metaphase of the cell cycle.•DDX3 protein expression is also upregulated during early mitosis.