In a day 7 UUO study, CypB−/− mice showed a reduced interstitial macrophage infiltration; however, there was a surprising lack of histologic evidence of renal fibrosis in this model, and the modest upregulation of collagen I and TGF-β1 mRNA levels seen on day 7 UUO in WT mice were unaffected by CypB deletion [41]. Here, TGFB1 is linked to renal fibrosis.