Importin-8 is a member of a class of approximately 20 potential Ran targets that share a sequence motif related to the Ran-binding site of importin-beta. It acts as a nuclear protein involved in the nucleolar transport. Importin-8 is required for cytoplasmic miRNA-guided gene silencing and is involved in loading Ago complexes into a variety of different mRNA targets, affecting the nuclear localization of Ago proteins. This protein binds to the nuclear pore complex and, along with RanGTP and RANBP1, inhibits the GAP stimulation of the Ran GTPase. The importin-alpha/beta complex and the GTPase Ran mediate nuclear import of proteins with a classical nuclear localization signal. Importin-8 has been proposed previously as a reference gene in the human motor cortex as it showed no differences in a study with different brain regions from chronic alcoholics and control subjects and lung samples.