In contrast to the observations in Pax8-HIPK2WT UUO kidneys, the kidneys of Pax8-HIPK2KD-UUO mice showed a marked reduction in renal fibrosis (Figure 4, A and B), which was associated with reduced Smad3 activation and expression of profibrosis markers (Figure 4, C and D). The gene discussed is SMAD3; the disease is renal fibrosis.