Fig. 8. Reduction of C/EBPβ expression induces reduction of ATRA-induced differentiation of NB4 cells. (A) C/EBPβ expression was evaluated by northern blot after 4 h of ATRA treatment in two different pools of cells transfected with the RNAi vector MSCV-U6-beta (pool1 and pool2) in comparison with cells transfected with an empty vector MSCV-U6 (ev). Cell maturation after 5 days of ATRA treatment was evaluated by morphology using MGG staining (B) and/or by NBT reduction assay (C). Results are presented as the percentage of NBT-positive cells and correspond to a count of 500 cells.