Effect of expression of WT C/EBPα (dark grey bars), mutated C/EBPα on N-terminal (light grey) and on C-terminal (black) was evaluated on mouse hematopoietic progenitors by Colony Forming Units assay. 2×103 mouse hematopoietic progenitors (mLin− cells) after transduction were plated in M3434 medium; one week later number and type of CFUs were determinate. Serial replating was performed to evaluate secondary, tertiary, fourth or fifth CFUs respectively. Numbers of transduced CFU by Control (white bar), WT C/EBPα (dark grey), N-terminal (light grey) and C-terminal (black) are represented. The increase in colonies after serial replating observed could be explained by the presence of live immature cells in the methylcellulose, which were able after replating to mature and give rise to CFUs. Results are shown as mean ± standard deviation (SD), with significant differences of p ≤ 0.05, p ≤ 0.01 or p ≤ 0.001 are indicating by (*), (**) or (***) respectively.