Posttranscriptional increase in ferritin expression in the liver of IRP2-deficient mice. Expression of ferritin H- and L-subunits was analyzed in groups of 4 +/+, +/-, and -/- mice by Western (top panels) and Northern (bottom panels) blotting using β-actin as a standard. IRP2 expression is also shown; a nonspecific band is indicated with an asterisk. The Western blot and Northern blot signals were quantified and results are presented in a histogram (bottom) after normalization for β-actin. Error bars indicate standard deviation. Ferritin H-chain was below the detection limit in wild-type mice (nd) and was not quantified in Irp2^-/- mice (nq) because of background interference. These figures are representative of data obtained with 3 independent lots of mice (including 4 +/+ and 4 -/- animals each).