AQP-1 is released in association with exosomes during in vitro maturation of reticulocytes and in vivo. (A) Reticulocytes (10⁶ cells) before (t0) and after 48 hours (t48) in vitro maturation (left); top and bottom fractions were collected after cell separation on a Percoll gradient (right) were subjected to SDS-PAGE, followed by immunoblotting for the proteins indicated. (B) Exosomes (50 μg protein) released during in vitro maturation (left lane) or isolated directly from the plasma of anemic mice (right lane) were subjected to SDS-PAGE, followed by immunoblotting for the proteins indicated.