RUNX3 binds to and transactivates the CD11a promoter through recognition of the AML-110 element. (A) EMSA was performed on the MS7 oligonucleotide probe using nuclear extracts from COS-7 cells transfected with the indicated factors (C/EBPα42, CBFβ, RUNX1+CBFβ, RUNX3+CBFβ, or RUNX2+CBFβ) or from undifferentiated or differentiated myeloid (U937 or THP-1) cells. The position of RUNX1- and RUNX3-containing complexes is indicated. (B) EMSA was performed on the MS7 oligonucleotide probe using nuclear extracts from COS-7 cells transfected with RUNX3+CBFβ or differentiated THP-1 cells and in the absence or in the presence of polyclonal antisera against C/EBPα, RUNX1, or RUNX3. The position of C/EBPα- and RUNX3-containing complexes is indicated. (C) K562 cells were transfected with 1 μg of the indicated reporter vector together with 400 ng pCGN–AML-2 (RUNX3) plus CDM8-CBFβ. “Fold induction” represents the luciferase activity produced by each expression vector combination relative to the activity produced by 400 ng CMV-0 plus empty pCGN. Data represent mean ± SD of 3 experiments using distinct DNA preparations (*P = .01 for pCD11A170-Luc activity in the presence of the RUNX3 expression vector versus pCMV-0; *P = .01 for RUNX3 transactivation on mutant constructs compared with transactivation on pCD11A170-Luc).