Argutus AKI Test (rat) includes αGST, GSTYb1, and RPA-1, the combination of which enables the site of acute kidney injury to be identified more easily than traditional tests. Glutathione S-transferases (GSTs) are proteins found in high concentrations in the luminar cells of the proximal and distal tubules. αGST is found in the proximal tubule while GSTYb1 localizes in the distal tubule. These proteins are not released in the healthy rat and as such act as a very sensitive indicator of site specific injury. Renal Papillary Antigen 1 (RPA-1) is a urinary biomarker for injury to the luminal epithelial cell of the collecting duct.