Tfr1 is not the main contributor to hepatocellular iron uptake. (A) Twelve-week-old male Tfrc^Alb-Cre mice and control Tfrc^fl/fl littermates (n = 8 for each genotype) were injected intraperitoneally with ⁵⁹Fe-transferrin. Six hours later, the animals were sacrificed. Blood was collected, and tissues were dissected following perfusion with phosphate buffered saline to remove residual blood. The distribution of ⁵⁹Fe radioactivity was analyzed in a gamma counter. (B) Primary hepatocytes isolated from Tfrc^Alb-Cre mice and control Tfrc^fl/fl mice were incubated with ⁵⁹Fe-transferrin for 24 hours. Cell-associated radioactivity was measured in a gamma counter. Data in (A-B) are mean ± standard error of the mean. Statistical analysis was performed using 2-way ANOVA (A) and the Student t test (B). (C) Immunofluorescence detection of Tfr2 and the late endosome marker Rab7; colocalization is shown by the white arrowheads. Scale bar, 2 μm; original magnification ×63.