This peptide contains the nuclear localization sequence (NLS residues 360-369) of the transcription factor NF-κB p50 linked to a peptide cell-permeablization sequence, the hydrophobic region (h-region) of the signal peptide of Kaposi fibroblast growth factor (K-FGF). SN50 inhibits translocation of the NF-κB active complex into the nucleus. In mouse endothelial LE-II cells induced with LPS, inhibition of NF-κB nuclear translocation was 88% at 50 µg/ml (18 µM). In human monocytic THP-1 cells induced by LPS or TNFα there was 85% inhibition at 100 µg/ml.