Transduction of CD34⁺ progenitors with the C/EBP-ϵ^32/30 activator isoforms blocks expression of the C/EBP-ϵ¹⁴ repressor isoform. CD34⁺ cells were transduced for 72 hours with the C/EBP-ϵ^32/30 (lane 1) or empty GFP (lane 2) retroviral vectors and grown in suspension cultures supplemented with IL-5 to drive eosinophil differentiation. Total protein and RNA was prepared at 14 days from 10⁶ cells lysed in TRIzol (Invitrogen) and analyzed by Western blotting (A) for expression of the C/EBP-ϵ^32/30 and ϵ¹⁴ isoforms, or semiquantitative RT-PCR (B) for expression of the C/EBP-ϵ¹⁴ repressor isoform. Western blotting for GAPDH was used to control for equal protein loading (A), and PCR for β₂M was used for comparison of cDNA inputs (B). Vertical lines have been inserted in panel A to indicate repositioned gel lanes.