TfR2 protein levels are modulated by iron status in vivo. Rats were made either iron deficient (A) or iron loaded (B) by diet as described in “Materials and methods.” After the rats were humanely killed, lysates were prepared from liver tissue for Western blot analysis. TfR2, TfR1, ferritin, and actin levels are shown for age- and diet-matched control and iron-deficient rats and for age- and diet-matched control and iron-loaded rats. Each lane shows lysates from individual animals for iron-deficient rats (n = 6) versus control rats (n = 4) and for iron-loaded rats (n = 5) versus control rats (n = 5).