TfR2 protein levels in genetic models of hepatic iron loading. Hepatic tissue was obtained for 3 different mouse models: 10-week-old Hfe^-/- mice, a genetic model of human hereditary iron overload due to loss of Hfe function, 4- to 5-week old Trf^hpx/hpx mice, which have impaired Tf synthesis, and 6-week-old Hbb^th-1 mice, which have defective globin synthesis. Controls for the latter group included 2 wild-type and 2 heterozygous HRI^+/- mice that were both Hbb^wt; all Hbb^th-1 mice were wild type for HRI.²⁹  After Western analysis, TfR2 protein levels were determined by densitometry using Quantity One software (Bio-Rad) to compare expression levels; shown are mean values (± SEM) normalized to actin (loading control). The numbers of mice for each group are noted in the figure. ^*different from control, P < .05. The increase in TfR2 levels determined for Hfe^-/- mice may be an underestimate because a small increase in actin levels was noted for these animals.