The GTPase Ran is a small protein that belongs to the RAS protein superfamily and is found associated with the nuclear membrane. Ran GTPase is essential for mRNA processing, nuclear transport, cell cycle control, mitotic spindle assembly, and postmitotic nuclear re-assembly and nuclear architecture maintenance. Ran binding proteins (RanBPs) belong to a family of proteins that bind Ran GTPase and help to stimulate its GTPase activity. Members of the RanBP family show weak similarity to importin beta, a protein involved in the transport of proteins to the nuclear membrane. Recently it has been shown that RanBP3 function is regulated by the Ras/ERK/RSK and PI3K/Akt signaling pathway. This finding has provided a link between nuclear transport, cell signaling, and cell fate.