Effects of rHuEpo on EA.hy926 cell proliferation. Cells were seeded at 2 × 10³ cells per well. After 24 hours, medium was removed and replaced every other day with fresh medium containing 0.25% FCS and supplemented 1:1 (vol:vol) with RPMI-1640 medium containing increasing concentrations of rHuEpo. The cell number was counted at day 6 of growth. The experiment was performed in quadruplicate and values are shown as the mean ± SD.