DNA binding of Sp1. (A) Constitutive binding to the DNA of Sp1 in non-CF C38 cells and an isogenic CF IB3-1 cell line and in non-CF 16HBE14o- S1 cells and an isogenic CF 16HBE14o- AS3 cell line. (B) Effect of the treatment with AZM on the DNA binding of Sp1 in CF cells (IB3-1, 16HBE14o- AS3, and 2CFSMEo-). Sp1 DNA binding activity was analyzed using a commercial kit following the manufacturer's instructions. The experiment was repeated three times (means ± SD). *, P < 0.05; **, P < 0.01. OD, optical density.