Rab17 belongs to the Rab family of small Ras-like GTPases. It is specifically expressed in epithelial cells and is upregulated during cell polarization. Immunofluorescence staining studies indicate that Rab17 is associated with the perinuclear recycling endosome in nonpolarized epithelial cells and with the apical recycling endosome in polarized epithelial cells. The function of Rab17 remains unclear. Reports of Rab17 colocalization with internalized IgA in the apical endosome suggest that it may regulate receptor-mediated transcytosis. Rab17 has also been shown to regulate melanocytic filopodia formation and melanosome trafficking. siRNA knockdown of Rab17 in melanoma cells induces melanosome accumulation in the cell periphery.