title: Erratum.
abstract: In the report "Induction of hemoglobin accumulation in human K562 cells by hemin is reversible" by A. Dean et al. (24 Apr., p. 459), the second sentence in the legend for figure 1 should have read: "A stock solution of 600 microM hemin was prepared by adding 0.3 ml of 1N NaOH to 19.56 mg of hemin, and then adding 0.3 ml of 0.5M tris base, 2.5 ml of cell growth medium, and 0.35 ml of 1N HCI, and then diluting to a final volume of 50 ml with cell growth medium."