Retromer is an evolutionarily conserved multimeric protein complex that mediates intracellular transport of various vesicular cargoes and functions in a wide variety of cellular processes including polarized trafficking,developmental signaling and lysosome biogenesis.Through its interaction with the Rab GTPases and their effectors,membrane lipids,molecular motors,the endocytic machinery and actin nucleation promoting factors,retromer regulates sorting and trafficking of transmembrane proteins from endosomes to the trans-Golgi network(TGN) and the plasma membrane.In this review.I highlight recent progress in the understanding of relromer-medialed protein sorting and vesicle trafficking and discuss how retromer contributes to a diverse set of developmental,physiological and pathological processes. Retromer is an evolutionarily conserved multimeric protein complex that mediates intracellular transport of various vesicular cargoes and functions in a wide variety of cellular processes including polarized trafficking, developmental signaling and lysosome biogenesis. Through its interaction with the Rab GTPases and their effectors, membrane lipids, molecular motors, the endocytic machinery and actin nucleation promoting factors, retromer regulates sorting and trafficking of transmembrane proteins from endosomes to the trans-Golgi network (TGN) and the plasma membrane. In this review. I highlight recent progress in the understanding of relromer-medialed protein sorting and vesicle trafficking and discuss how retromer contributes to a diverse set of developmental, physiological and pathological processes.