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 sets of downstream effectors directly responsible for vesicle formation, movement, tethering and fusion (PubMed:21775604, PubMed:30771381). RAB27B regulates homeostasis of late endocytic pathway, including endosomal positioning, maturation and secretion (PubMed:30771381). Plays a role in NTRK2/TRKB axonal anterograde transport by facilitating the association of NTRK2/TRKB with KLC1 (PubMed:21775604). May be involved in targeting uroplakins to urothelial apical membranes (By similarity). {ECO:0000250|UniProtKB:Q8HZJ5, ECO:0000269|PubMed:21775604, ECO:0000269|PubMed:30771381}. This is the function of RAB27B (RAB27B, member RAS oncogene family, Ensembl gene identifier ENSG00000041353).