Stx1-induced nuclear translocation of AP-1 complexes. Differentiated THP-1 cells were incubated with Stx1 (400 ng/mL), LPS (200 ng/mL), or TPA (200 ng/mL) for 2 hours. Nuclear extracts were prepared and AP-1 translocation was assessed by electrophoretic mobility shift assay using a radiolabeled consensus AP-1 binding site probe. Specificity of binding was determined by competition with cold probe and by the use of an oligonucleotide containing a substitution in the AP-1 binding motif.