Liver Hamp mRNA is reduced at 12 days of age in mice lacking 2 to 4 Smad1/5 alleles but is reduced at 8 weeks of age only in double-knockout mice. Relative expression of Hamp was measured in Smad5^fl/fl;Cre⁺, Smad1^fl/fl;Cre⁺, Smad1^fl/wt;Smad5^fl/fl;Cre⁺, Smad1^fl/fl;Smad5^fl/wt;Cre⁺, Smad1^fl/fl;Smad5^fl/fl;Cre⁺, and littermate control Cre⁻ mouse livers at 8 weeks (A-B; n = 5-11 per group) or 12 days (C-D; n = 3-6 per group) of age. Transcript levels were normalized to Rpl19, and the average of the respective littermate Cre⁻ control mice was set to 1. Values represent mean ± standard error of the mean. *P < .05; **P < .01; ***P < .001 relative to the respective Cre⁻ controls by Student t test.