1x binding buffer, 20 mM Tris, pH 7.5, 50 mM KCl, 1 mM EDTA, 1 mM DTT, 0.10% NP40, 6% glycerol, 0.1 mg/mL BSA and 50 ng/μl poly dI-dC) and were then electrophoresed through a 6% DNA retardation gel at 100V for 90 minutes.