RT-PCR of SCL, E2A, Id2, 18S rRNA, and β-globin. Results of studies on day 7, 10, and 14 BFU-E–derived cells from a representative normal donor and from day 10 and 14 cells from two patients with transfusion-dependent DBA. BFU-E were stimulated with or without 100 ng/mL SCF. The same patients (1 and 2) studied in Figs 2, 3, and 4 are shown for comparison of protein and mRNA levels.