Expression of Bmp6, Smad7, Id1, Atoh8, and Hamp1 in the livers of mice with genetic iron overload. Mice with liver-specific knockout of Smad4 (A) or Hamp1 disruption (B) were compared with their respective controls. Expression levels were normalized to HPRT and log2 transformed for the statistical analyses. Statistically significant differences relative to the controls were determined by Student t tests. *P < .05; **P < .01; ***P < .001. Geometric means (2ⁿ, where n is the mean of the log2-transformed expression measures within each group) (± SD) are represented on this figure, relative to the geometric mean of the appropriate control group.