NF-κB inhibitor is a synthetic peptide corresponding to the nuclear localization sequence (NLS) of NF-κB p105 subunit (also known as p50) appended to a hydrophobic sequence to facilitate import into living cells. It blocks the nuclear import of p105 in cells treated with activators of NF-κB signaling, including LPS and TNF-α. NF-κB control is a peptide that is identical in sequence to NF-κB inhibitor, except two essential, basic residues of the p105 NLS are substituted with non-basic amino acids. It is ineffective at blocking the activation of NF-κB signaling and is used as a negative control peptide.