SMURF2 and autosomal recessive polycystic kidney disease: In control cultured collecting duct cells and in WT mouse and human kidney specimens, Smurf2 was found primarily in small vesicles but in the mutant cultured cells and ARPKD tissues it was localized to large vacuole-like structures that also stained for the lysosomal marker Lamp2 (Fig. 3).