ACTA1 and fibrosis: We found that HK-2 cells displayed phenotypic transition of epithelial-mesenchymal transition (EMT), which is an important feature of fibrosis, characterized by down-regulated levels of epithelial protein marker (E-cadherin), up-regulated levels of mesenchymal protein marker (vimentin and α-SMA), and ECM proteins (fibronectin and collagen IV) (Figure 1A and 1B).