Nuclear protein extracts are comparable to those prepared by a standard large-scale method. Adherent rat thyroid FRTL-5 cells were stimulated by 50 nM TPA for 30 minutes. Nuclear proteins were subsequently purified using the new small-scale method (lanes 1 and 2) or an established large-scale method  (lanes 3 and 4). Whole cellular protein was also isolated  from TPA-treated cells to illustrate the presence of the cytoplasmic form of NF-κB (lane 5). EMSA was performed using an NF-κB-specific DNA probe.