GDP-dissociation inhibitor preventing the GDP to GTP exchange of most Rab proteins. By keeping these small GTPases in their inactive GDP-bound form regulates intracellular membrane trafficking (PubMed:25860027). Negatively regulates protein transport to the cilium and ciliogenesis through the inhibition of RAB8A (PubMed:25860027). . This is the function of GDI2 (GDP dissociation inhibitor 2, ENSG00000057608).