Further studies also revealed that moderate renal fibrosis, as indicated by the expression of α‐SMA, collagen I and fibronectin mRNA and the accumulation of the corresponding matrix proteins, occurred in UUO vehicle mice but was substantially attenuated in mice that received petA (40 mg/kg) 4 days before or immediately after UUO operation (Figure 3). This evidence concerns the gene ACTA1 and renal fibrosis.