Epo induction by PHIs. (A) Fold increase of epo in 1G6 cells following 24-hour incubation with the indicated PHI at 3 or 10 μM. The data are presented as fold induction above vehicle control (DMSO), which was set at 1. The epo levels observed in DMSO-treated cell cultures ranged from 3 to 12 mIU/mL and from 30 to 400 mIU/mL in PHI-treated cultures. (B) The mean fold increase in logarithmic scale of plasma epo levels in Swiss Webster mice 4 hours after intravenous administration of PHI (n = 3 mice per group). Results are expressed as fold increase over levels determined in vehicle control–treated animals. Error bars are SE.