Effects of CuSO4, ZnCl2, BCS, and CdCl2 on Sp1-probe binding. [A] Sequences of wild-type (WT) used as the probe and a mutant (MT) used as competitor, The box contains GC-rich Sp1-binding site. [B] Identification of Sp1-probe complex by GEMS. [C] Competition of Sp1-probe binding by increased concentrations of different metal salts and BCS as indicated (lanes 1 to 6 correspondingly represent 0, 1, 10, 50, 100, and 200 µM, in each panel, using 100 µM as reference a point, arrow).