Labelled Ro 106-9920 (R637500). Ro 106-9920 is an inhibitor of NF-κB activation, possibly via selective inhibition of LPS- and TNF-α-induced IκBα ubiquitination (IC50 = 3 μM). Ro 106-9920 blocks subsequent production of TNF-α, IL-1β and IL-6. Inhibits mucin production in an in vitro model of COPD, and is anti-inflammatory following oral administration in vivo. Also weakly inhibits EGFR, 5-lipoxygenase and iNOS.