Colocalization rate between PCX and EGFP-Rabs (or Myc-Rab40C) in 2D MDCK II cells is shown by ++ (very high colocalization), + (partial but clear colocalization), +/− (partial and less colocalization), and − (no colocalization). ND, not determined because of very low expression level of Rab6C, Rab40A, and Rab40B in MDCK II cells. Detailed image data for each Rab are shown in Figs. 3 and S3. The nomenclature of mammalian Rabs in this study is as described in Itoh et al. (2008).