Effect of IGFBP-3 on ATRA-induced levels of C/EBPϵ transcripts in NB4 cells. Cells were cultured for 2 days with IGFBP-3 (5 μg/mL), ATRA (10^–7 M), or both in combination. RNA was extracted. cDNA was synthesized and subjected to real-time PCR to measure the levels of C/EBPϵ transcripts. Data represent the mean ± SD of triplicate cultures.