E47 Expression in transfusion-dependent DBA. Western blot analysis of E47 in day 10 or 14 BFU-E–derived cells from six normal donors and six patients with DBA cultured with or without 100 ng/mL human SCF is shown here. The cell lysate from 2 × 10⁵ BFU-E–derived cells was loaded onto each lane of a 7% polyacrylamide gel and immunoblotting performed as described in Materials and Methods.