Background: The regulation of GTPase activity is achieved via activators called GEFs (guanine-nucleotide exchange factors) and inactivators called GAPs (GTPase-activating proteins). Ran-specific GTPase-activating protein 1 (RanGAP1) induces the GTPase activity of the RAN small GTPase. The Ran GTPase plays a role in spatial information and nucleocytoplasmic transport. RanGAP1 is the antagonist of the GEF RCC1 which keeps RAN in the active GTP-bound state.