Generation of Hbb-Erfe mice and analysis of Erfe overexpression. (A) Structure of the transgene construct. Bone marrow Erfe mRNA in 6-week-old mice (B) and 16-week-old mice (C). Serum ERFE levels of 6-week-old mice (D) and 16-week-old mice (E). Relationship between serum ERFE protein levels and marrow Erfe mRNA in 6-week-old mice (F), regression line Y = 3.18* X^2.5 (r² = 0.51), and 16-week-old mice (G), regression line Y = 0.83* X^2.4 (r² = 0.57). In all panels, male = M (square) and female = F (circle); the mean of each group is shown by the blue line. TG = Erfe-overexpressing mice (line-L, pink symbols; line-M, red symbols; and line-H, dark red symbols); WT littermate controls are indicated by white symbols. Within each individual transgenic line, groups were compared by using two-way analysis of variance to determine significant effects (P < .05, bold red) of genotype (Gt) and sex on data variation and to identify interactions (Int) between these variables. Cohort numbers for mRNA and serum analysis are shown. For significant Int, the effects of Gt in males and females were analyzed using Šidák’s multiple comparisons test: *** P < .001, **** P < .0001