Fibrosis in the kidney is one of the key causes of progressive renal failure. High levels of the inflammatory molecule TGF-β1 in the kidney tubules due to tissue damage can cause fibrosis as well as nephron degeneration, resulting in loss of kidney function. To clarify the mechanisms regulating TGF-β1-mediated renal fibrosis, Koesters et al expressed high levels of TGF-β1 in renal tubules of mice. Nephron degeneration in this system was mediated by decomposition of the tubular cells. These data suggest that TGF-β1 may play a novel role in cell death of renal cells, thus contributing to renal fibrosis.