The expression of TGF-β1 and TGF-β1-regulated genes were increased at more advanced stages of polycystic kidney disease but was nearly unaltered at the early stage of the disease in four PKD animal models, suggesting that the TGF-β1 signalling pathway was probably not implicated in initial steps of cyst formation but contributed to progression of polycystic kidney disease [5]. The gene discussed is TGFB1; the disease is polycystic kidney disease.