ACTA1 and fibrosis: As shown in Figure 2, the expressions of both fibronectin, a major ECM protein and a fibroblast chemoattractant [26], and αSMA, a tubulointerstitial fibrosis marker in UUO kidney [2], were barely detectable in the kidneys of sham WT or sham KO mice, but prominently elevated in the WT mice after UUO on day 14.