ACTA1 and renal fibrosis: It is now generally accepted that the initial histological hallmark of renal fibrosis progression is the accumulation of myofibroblasts in the renal interstitium, which is typically characterized by the secretion of α-SMA and its further internalization to form stress fibers and the production of collagen I. The expression of α-SMA by renal tubular epithelial cells during EMT is used to identify EMT by immunostaining, thus demonstrating the existence of this process (Strutz et al., 1995; Iwano et al., 2002; Cheng et al., 2006; Tyler et al., 2006).