ATP6AP2 and chronic kidney disease: Additionally, higher levels of the 28 kDa product, sPRR, produced by protease-mediated cleavage of PRR, which indicates active RAS, have been seen in CKD patients (Cousin et al., 2009; Yoshikawa et al., 2011; Fang et al., 2017; Gatineau et al., 2019; Xie et al., 2020).