SMAD7 and polyostotic fibrous dysplasia: Following that, in vitro and in vivo dual model experiments with PFD intervention revealed that PFD alleviated tubulointerstitial fibrosis in unilateral ureteral obstruction (UUO) rats by down‐regulating miR‐21 expression and up‐regulating Smad7 expression, which ultimately inhibited the activation of the TGF‐β1/Smad3 signaling pathway.