ACTA1 and renal fibrosis: Immunohistochemistry revealed that compared with the saline-treated mice, chronic ANG II infusion resulted in renal fibrosis in WT mice, as demonstrated by a significant increase in collagen I and α-SMA expression in both mRNA and protein levels, and the accumulation of α-SMA+ myofibroblasts in the tubulointerstitium (Fig. 2).