The Rab subfamily of small GTPases plays an important role in the regulation of membrane trafficking. RAB17 is an epithelial cell-specific GTPase. The small GTPases Rab are key regulators of intracellular membrane trafficking, from the formation of transport vesicles to their fusion with membranes. Rabs cycle between an inactive GDP-bound form and an active GTP-bound form that is able to recruit to membranes different set of downstream effectors directly responsible for vesicle formation, movement, tethering and fusion.