Oligonucleotide pull-down assay using the Gfi-1/C/EBP probe in the HNC promoter. Nuclear extracts prepared from uninduced and ATRA-induced MPRO cells (a murine myeloid cell line for neutrophil maturation) were incubated with the biotinylated Gfi-1/C/EBP probe from the HNC promoter (A). The DNA-protein complexes were recovered using streptavidin-agarose beads and the bound proteins resolved by SDS-PAGE and Western blot analysis. The blot was probed sequentially with Gfi-1, C/EBPα, and C/EBPϵ antibodies (B). Oligonucleotide pull-down assays using the same probe and 293 extracts overexpressing Gfi-1, C/EBPα, and C/EBPϵ served as a positive control (C). (− indicates untransfected 293 cells; +, transfected 293 cells.)