PTGS2 and thyroid cancer: To validate the probable prediction of the interaction between TFAP2B and the COX-2 promoter, we pulled down the nuclear proteins bound to the COX-2 promoter in thyroid cancer cells using the 5′-biotin-labeled COX-2 promoter probe or a nonspecific probe (NSP) and streptavidin–agarose beads and used western blotting to detect TFAP2B in the nuclear protein/DNA complex with a TFAP2B-specific antibody.