AT-II contributes to renal fibrosis through TGF-β1 gene induction, an increased release of TGF-β1 and via induction of receptors for TGF-β1.13 TGF-β1 is responsible for the activation and proliferation of myofibroblasts and progression of renal fibrosis, as it induces the synthesis of the matrix proteins collagen type I (COL1) and tenascin-C (TNC)14,15 and mRNA expression of trombospondin-1 (TSP-1, also known as THBS1)15 in human kidney tubule cells. Here, THBS1 is linked to renal fibrosis.