IL1 beta activity was assessed by its ability to induce the activation of the NF-kB pathway. IkBa degradation was detected by Western blotting. HeLa cells were grown to confluence in 6 well plates. IL-1b was diluted at the indicated concentrations in 500µl DMEM/Nut.Mix.F-12 10% fetal calf serum and added to the wells after being washed once with the same media. Cells were collected after 30 min and lysed. 100µg of cellular extract were separated on a SDS-PAGE and transferred on a nitrocellulose membrane. IkBa degradation was detected with a rabbit polyclonal antibody to IkBa and a goat anti-rabbit HRP-conjugated secondary antibody. Degradation of IkBa was detected at 10pg/µl IL1 beta, under these conditions.