Quantitative RT-PCR analysis of globin mRNAs from normal human erythroid cultures. (A-B) Normal erythroid precursors were harvested from untreated control cultures or cultures treated with either 150 μM HU or 20 nM MTH. Total RNA was reverse transcribed and 50 ng used for PCR amplification. For each sample, the ΔRn for γ-globin (A) or GAPDH (B) is plotted against the cycle number. □ indicate RNAfrom control untreated cultures; ○, RNA from HU-treated cultures; and ▪, RNA from MTH-treated cultures. (C-E) The data obtained were analyzed using the Sequence Detection Software System 1.6.3, and the fold increase of γ-globin (C), β-globin (D), and α-globin (E) mRNA in cultures treated with HU or MTH compared with untreated cultures (taken as 1) was calculated. Data were derived from quantitative RT-PCR plots using GAPDH mRNA as reference and expressed as average ± SD of 4 independent RT-PCR analyses on a same donor sample (P < .001 when data from panel C of MTH-treated cells are compared with those of HU-treated or untreated control cells). (F) Fold increase of γ-globin, β-globin, and α-globin mRNA in cultures treated with MTH compared with untreated cultures. Data were derived from quantitative RT-PCR plots using GAPDH mRNA as reference and expressed as average ± SD of 5 independent experiments using different human donors (P < .001 when data of γ-globin mRNA content are compared with either β-globin mRNA or α-globin mRNA content).