Hypoxia and PHD inhibition stimulate hepatic Epo production in P3Pro mutants. Shown are Epo mRNA levels in livers from P3Pro mutants and wild-type (Wt) littermate controls. (A) Exposure to acute anemic hypoxia induced by phlebotomy (log scale; measurements 24 hours after phlebotomy). Shown also is a statistically significant association between the linear decline in Hct value and the exponential increase in hepatic Epo mRNA levels in P3Pro mutants (right; R² = 0.61, P < .01). (B) Exposure to chronic normobaric hypoxia (10% O₂ for 10 days). (C) Oral administration of PHD inhibitor GSK1002083A (PHI) for 2 days. Wt refers to Cre-negative littermates. *P < .05, **P < .01, ***P < .001; ns, not statistically significant.