Serum and tissue iron levels are increased in Alk2^fl/fl; Alb-Cre and Alk3^fl/fl; Alb-Cre mice. (A) Hepatic Alk2 mRNA levels were measured in Alk2^fl/fl and Alk2^fl/fl; Alb-Cre mice, and Alk3^fl/fl and Alk3^fl/fl; Alb-Cre mice. Mice carrying the Cre recombinase transgene are indicated by “Cre.” *P < .0001, Alk2^fl/fl; Alb-Cre versus Alk2^fl/fl. (B) Hepatic Alk3 mRNA levels were measured in Alk2^fl/fl, Alk2^fl/fl; Alb-Cre, Alk3^fl/fl and Alk3^fl/fl; Alb-Cre mice. *P = .001, Alk3^fl/fl; Alb-Cre versus Alk3^fl/fl. (C) Serum iron concentration measured in all 4 genotypes (n ≥ 8 per group). *P = .04, Alk2^fl/fl; Alb-Cre versus Alk2^fl/fl. ^#P = .04, Alk3^fl/fl; Alb-Cre versus Alk3^fl/fl. (D) Transferrin saturation measured in all 4 genotypes (n ≥ 8 per group). P = .054, Alk2^fl/fl; Alb-Cre versus Alk2^fl/fl. *P = .049, Alk3^fl/fl; Alb-Cre versus Alk3^fl/fl. (E) Liver iron content measured in all 4 genotypes (n ≥ 8 per group). *P = .0025, Alk2^fl/fl; Alb-Cre versus Alk2^fl/fl. ^#P = .0005, Alk3^fl/fl; Alb-Cre versus Alk3^fl/fl. (F) Spleen iron content measured in all 4 genotypes (n ≥ 8 per group). *P = .04: Alk3^fl/fl; Alb-Cre versus Alk3^fl/fl.