(A) Comparison of DNA binding affinity of C/EBPɛ (p32) and C/EBP to neutrophil elastase C/EBP site. EMSA study with³²P γ-ATP–labeled C/EBP binding site oligonucleotide from the neutrophil elastase promoter and either C/EBPɛ or C/EBP expressed in COS-1 cells. The same amount of protein was incubated with decreasing concentrations of hot oligonucleotides (left to right). β emissions of the retarded bands and the free hot probe were quantitated by an AMBIS imaging system. (B) and (C) show the Scatchard analyses of the data for C/EBPɛ and C/EBP, respectively. The slope of the curves express the affinity of the protein for the DNA motif. kd: −1/slope: C/EBPɛ: 4.2 nmol/L; C/EBP: 0.65 nmol/L.