Fig. 4.

Effect of LA CS on nuclear protein binding to potential activating protein 1 (AP1) cis elements of Pgp promoter in Caco-2 cells. Nuclear extracts (8 μg) from control (untreated) or LA CS-treated (1:10 dilution, 24 h) Caco-2 cells were incubated with the digoxigenin (DIG)-labeled AP1 cis elements of Pgp promoter, namely, AP1a (proximal, −119/−98 bp, lanes 2 and 3), AP1b (distal, −99/−78 bp, lanes 6 and 7), or AP1c (+175/+196 bp, lanes 10 and 11). Protein-DNA complexes competed in the presence of an excess of cold unlabeled oligonucleotide probe (lanes 4, 8, and 12) showing specificity of binding. Representative gels of 3 separate experiments with similar results are shown.