TGFB1 and cyst: To support our hypothesis, we generated Pkd1nl/nl:MIF−/− mice and found that knockout of MIF not only slowed cyst growth as characterized by decreased cyst index, KW/BW ratios, and BUN levels (Figure 5A–D), but also decreased interstitial fibrosis and α-SMA deposition (Figure 5E), as well as the mRNA expression of TGF-β, Col I and Col III in kidneys of PN28 Pkd1nl/nl:MIF−/− mice versus Pkd1nl/nl:MIF+/+ mice (Supplemental Figure S5).