SMAD7 and myalgic encephalomeyelitis/chronic fatigue syndrome: The expression of the wild-type luciferase-Smad7-3′UTR reporter was remarkably lower than the mutant luciferase-Smad7-3′UTR reporter and control plasmid (Fig. 5a, b), suggesting that Smad7 is a validated miR-21 target in CFs and that miR-21 can inhibit Smad7 expression, leading to the further amplification of TGF-β1 signaling.