Sirtinol also blocked the inhibitory effect of losartan on the UUO-induced renal fibrosis, suggesting that the anti-fibrotic effect of losartan might be mediated at least in part through inhibition of ER stress via up-regulation of SIRT1, followed by induction of HO-1 and thioredoxin (Figure 9). This evidence concerns the gene HMOX1 and renal fibrosis.