Surface expression of hAQP1, hAQP1 FLAG , hAQP1 C189S , rAQP3, hAQP7, hAQP8 and rAQP9 versus H 2 O-injected control oocytes. The surface expression of hAQP1, hAQP1 C189S mutant, rAQP3, hAQP7, hAQP8 and hAQP9 monomers (∼28 kDa) is shown by immunoreactive bands detected at a molecular weight (MW) between 25 and 37 kDa, using polyclonal antibodies (anti-AQP1, anti-AQP3, anti-AQP7, anti-AQP8 and anti-AQP9, respectively). The surface expression of hAQP1 FLAG monomer is shown by a band at a MW between 25 and 37 kDa, using a monoclonal antibody anti-FLAG. All the western blots show the absence of this immunoreactive bands in the H 2 O-injected control oocytes. Oocytes from 8–18 different frogs (i.e. batches of oocytes) were analyzed for surface expression, depending on the AQP construct used.