Differences in binding affinity of the nuclear proteins for the polymorphic sites. (A) EMSA of nuclear extract derived from HepG2 cells bound to the −401T fragment in the presence of increasing concentrations of unlabeled −402A fragment (lanes 2 to 5) or −401T fragment (lanes 7 to 10) as competitor. Arrows 1 and 2 refer to the allele-specific factors. Lanes 1 and 6, 0.20 mg/mL of HepG2 extract in the absence of competitor; lanes 2 to 5 and 7 to 10, 0.20 mg/mL of HepG2 extract in the presence of threefold (lanes 2 and 7), ninefold (lanes 3 and 8), 27-fold (lanes 4 and 9) and 81-fold (lanes 5 and 10) excess DNA as competitor. The intensity of the protein-DNA complexes 1 and 2 were quantified in three independent experiments. The relative intensities of the protein-DNA complexes 1 and 2 in the presence of increasing concentrations of unlabeled DNA fragments are shown in B and C, respectively. Line plots indicate mean values and standard deviations. The statistical significance of differences was determined by Student’s paired t-test. *P < .05; **P< .01.