Transactivation of the CD11a integrin gene promoter by C/EBP factors is dependent on both CEBP-100 and AML-110 elements. (A) THP-1 cells were transfected with the indicated reporter plasmids and luciferase activity determined after 24 hours. Promoter activity is expressed relative to the activity produced by the wild-type pCD11A170-Luc reporter plasmid in each transfected cell type after normalization for transfection efficiency. Data represent mean ± SD of triplicate determinations (*P = .03 for pCD11A170(–100mut)-Luc, P = .02 for pCD11A170(–110mut)-Luc, and P = 10^–5 for pCD11A170(–100/–110mut)-Luc when compared with the activity of the wild-type construct). (B) K562 cells were transfected with 1 μg pCD11A170-Luc together with increasing amounts (30, 100, or 300 ng) of CMV-0, CMV-C/EBPα42, or CMV-C/EBPβ expression plasmids. In all cases, total DNA was kept constant (1.5 μg) by adding CMV-0 plasmid DNA. Fold induction represents the luciferase activity produced by each expression vector relative to the activity produced by a similar amount of empty CMV-0 vector. Data represent mean ± SD of 3 independent experiments (*P = .05 compared with the activity of pCMV-0–transfected cells). (C) K562 cells were transfected with 1 μg of the indicated reporter plasmids and in the absence or presence of RUNX1/CBFβ, C/EBPα42, or C/EBPβ expression plasmids. For each individual reporter construct, fold induction represents the luciferase activity yielded by an expression vector relative to the activity produced by a similar amount of empty CMV-0 plasmid. Data represent mean ± SD of 3 independent experiments using distinct DNA preparations (*P < .05 compared with the activity of pCD11A170-Luc in the presence of RUNX1/CBFβ, C/EBPβ, or C/EBPα, respectively).