Effect of synthetic hepcidin injections on endogenous liver hepcidin expression. Mice were injected daily for 3 days with 0.15 M NaCl (controls) or hepcidin (100 μg) dissolved in 0.15 M NaCl, then liver samples were analyzed for hepcidin and GAPDH mRNA levels. The ratio of hepcidin to GAPDH is shown (means ± SEM). *P < .05.