AQP2 and acute kidney injury: In AKI caused by I/R, the secretion of aquaporin-1 and aquaporin-2 in urine exosomes is reduced, and the secretion of exosome-related markers such as Alix and TSG101 is increased at the later stage, suggesting that urinary exosome secretion increases during fibrosis (Asvapromtada et al., 2018).