Hypertonic stress progressively inhibits AQP-1 sorting into exosomes. (A) Mouse reticulocytes were cultured for 24 hours with or without sorbitol 75 mM. Exosomes were then collected, and both cells (10⁶) and exosomes (resuspended in the same volume of Laemmli buffer) were examined by SDS-PAGE and immunoblotted for the proteins indicated on the right. (B) Mouse reticulocytes were cultured for 24 hours, with increasing concentrations of sorbitol, and exosomes were collected, resuspended in the same volume of Laemmli buffer,²³  and examined by SDS-PAGE and immunoblotted for TfR and AQP-1.