Globin gene expression during phase II of the erythroid cell culture. Gene expression was determined by quantitative real-time RT-PCR, and the levels are related to fold change of the gene expression of one sample after normalization with HPRT gene expression. (A) Levels represent the mean values of the 12 and 14 individuals in the HPFH and control groups, respectively. (B) Relative ratios of gamma to β-globin gene expression. The γ and β values represent the average levels of all the individuals in each group.