Abstract: Objective To explore the role of transforming growth factor-β1/integrin- linked kinase/fibroblast-specific protein 1 (TGF- β1/ILK/FSP1) signaling pathway in cyclosporine A (CsA)-induced renal tubular epithelial cell transdifferentiation. Methods Rat renal tubular epithelial NRK-52E cells were induced with 1 mg/L CsA, treated with TGF-β1 inhibitor (SB431542, 10 μmol/L), or transfected with the ILK-RNAi lentiviral expression vector (ILKshRNA) or a negative control vector before CsA induction. The expressions of TGF-β1, ILK and FSP-1 mRNAs and proteins in the cells were detected using real-time PCR and Western blotting. The positive cells for α-SMA expression were detected by immunohistochemistry. Results Compared with the blank control cells, the cells treated with CsA showed significantly increased levels of TGF-β1, ILK and FSP-1 mRNAs and proteins (P<0.05). The expressions of TGF-β1, ILK and FSP-1 were significantly lower in TGF-β1 inhibitor group than in CsA group (P<0.05). The levels of ILK and FSP-1 were significantly decreased after shRNA-mediated ILK silencing (P<0.05). The number of positive cells for α-SMA was significantly lower in cells treated with SB431542 and in cells with ILK silencing than in the cells treated with CsA alone (P<0.05). Conclusion The activation of TGF-β1/ILK/FSP-1 signaling pathway is an important mechanism for CsA-induced transdifferentiation in rat renal tubular epithelial cells. ILK participates in CsA-induced epithelialmesenchymal transition of renal tubular epithelial cells.