The effects of increasing concentrations of diferric transferrin on NTBI uptake. Hepatocytes from Hfe KO (filled symbols) and control (open symbols) mice were incubated with ⁵⁹Fe-citrate (ratio of 1 μM Fe to 100 μM citrate) in the presence of Fe 0 to 20 molar ratio for diferric transferrin to Fe-citrate for 2 hours at 37° C. Internalized (•, ○) and membrane (▪, □) uptake are shown. Results are expressed as mean ± SD (n = 3). This graph is a typical representation from 2 independent experiments performed.