The effects of Sal B on E-cadherin mRNA expression, cell morphologic transformation and F-actin reorganization induced by TGF-β1 in HK-2 cells. (A) The effects of Sal B on E-cadherin mRNA expression. Real-time PCR analysis showed that TGF-β1 significantly suppressed E-cadherin mRNA expression in HK-2 cells, while 1 μM and 10 μM of Sal B prevented the loss of its expression (B) The effects of Sal B on cell morphology transformation and F-actin reorganization. HK-2 cells were incubated with serum-free medium or treated with (1) 2.5 ng/ml TGF-β1, (2) 2.5 ng/ml TGF-β1 plus 1 μM of Sal B, (3) 2.5 ng/ml TGF-β1 plus 10 μM of Sal B, (4) 2.5 ng/ml TGF-β1 plus 10 μM of SB-431542 for 24 h. HK-2 cells changed from a cuboidal to a spindle shape in response to TGF-β1, whereas treatment with 1 μM and 10 μM Sal B and SB-431542 blocked this morphologic transformation (×200). Representative micrographs of FITC-conjugated phalloidin staining showed significanat F-actin reorganization and the formation of abundant long stress fibers in HK-2 cells induced by TGF-β1 were formed. 1 μM and 10 μM of Sal B and SB-431542 significantly blocked these processes.