PPARA and Ureteral obstruction: Chau BN et al showed that miR-21 contributed to fibrogenesis and epithelial cells injury in the kidney of unilateral ureteral obstruction (UUO) and unilateral ischemia reperfusion injury (IRI) models, in which peroxisome proliferator activated receptor-α (PPARα), a direct target of miR-21, was involved [10].