Heph and Ireg1 expression is responsive to systemic rather than local iron levels. (A) Northern blot analysis of enterocytes from sla mice fed control diet (sla) and C57BL/6J mice fed control (Ctrl), iron-deficient (Fe^–), or iron-overload (Fe⁺) diets for 6 months. Blots were sequentially hybridized to probes for Heph, Ireg1, TfR, and Dmt1. The 18S rRNA band was used as a loading control. (B) Relative mRNA levels of Heph, Ireg1, TfR1, and Dmt1 were quantified using NIH Image and densitometry values normalized to values obtained for 18S. Data are means ± SD as percent control from 5 independent experiments. *P < .05 versus control.