SMAD7 and nutritional disorder: Consistent with the coregulation that has been proposed in the literature, the lower levels of hepcidin mRNA that were found in the FeD group were accompanied by down-regulation of hepatic Smad7 mRNA levels, which corroborates the idea that systemic and tissue iron deficiency lead to low hepcidin concentrations and consequently decrease Smad7 expression, the inhibitor of the BMP pathway.