MK-6482 attenuated polycythemia by reducing EPO levels in Vhl^R200W and Irp1-KO mice and in hypoxic Hep3b cells. (A) Serum EPO levels measured by ELISA were significantly increased in Vhl^R200W and Irp1-KO mice, but on treatment with the drug, the elevated EPO levels in Vhl^R200W and Irp1-KO mice decreased to normal WT levels. (B) Epo mRNA levels of Hep3b cells were more than 50-fold higher when grown at 2.5% oxygen concentration than levels grown at atmospheric oxygen concentrations, and the drug treatment significantly reduced the Epo expression levels. *P < .05; **P < .01; ***P < .001, by ordinary 1-way ANOVA (multiple comparisons). ns, not significant.