Figure 4

A sensitive IL-1 dose reveals PP2Ac to be constitutively active at the IKK complex. (A) Cells were left untreated or stimulated with decreasing doses of IL-1 for 15 min as indicated. The status of the initial IκBα degradation was determined by Western-blot analysis. (B) Cells were left untreated or stimulated with a sensitive dose of 0.5 ng/ml as derived from (A) for the indicated time points. Initial phosphorylation status of IKKβ as well as degradation of IκBα was documented by Western-blot analysis. (C) Cells were transfected with scrambled siRNA or siRNA specifically knocking down PP2Ac. 48 h later, cells were stimulated with 0.5 ng/ml IL-1 for the indicated time points, and phosphorylation status of IKKβ, degradation of IκBα and protein level of PP2Ac were analysed by Western-blot. In each analysis α-tubulin served as loading control. IKKβ phosphorylation was quantified using Image Quant software. Pooled data of three independently performed experiments are summarised. One representative Western-blot analysis is shown as Additional file 4.