To investigate the mechanism of defective translocation of AQP2-F204V, we turned to transfection of MDCK cells. Stable cell lines expressing mouse wild-type AQP2 and AQP2-F204V were established. Immunoblots of protein extracts from stable cell lines showed that MDCK cells recapitulate the glycosylation defect seen in mutant mice (unpublished data). The wild-type protein was again present in three different forms. Cells expressing AQP2-F204V lacked the 35–45 kDa form and were enriched in the core-glycosylated 31 kDa form.