How does Ran GTPase control both protein import during interphase and spindle attachment to the chromosomes during M-phase? It all has to do with its concentration gradient in the cell.

RanGDP is prevalent in the cytoplasm due to RanGAP and RanBPs to increase its GTPase activity. During import (left), importins bind to NLS-containing cargoes in the cytoplasm and translocate them ...