Fig. 6.

Inhibition of PI3K enhances but inhibition of GSK3β abolishes the IL-1β-induced activation of the canonical IKK2/IκB-α/NF-κB signaling pathway. Cultured rabbit colonic SMCs after serum starvation for 24 h were pretreated with the PI3K inhibitor LY-294002 (10 μM) plus the IKK2 inhibitor IKK2-IV (10 μM) or the IκB-α degradation inhibitor MG-132 (10 μM) or the GSK3 inhibitor LiCl (30 mM) for 1 h before treatment with or without IL-1β (10 ng/ml) for 15 min (A and C) or 3 h (B). Activation of NF-κB signaling was determined by Western blot analysis using the indicated specific antibodies (A and C). The expression of RGS4 mRNA was quantified by real-time RT-PCR with GAPDH normalization (B). **P < 0.01, significant decrease after IL-1β treatment by the inhibitors compared with DMSO. The number under each blot in A indicates the relative fold of optical density compared with the corresponding control.